Study of deterministic surface micro-texture generation in ultra-precision grinding considering wheel oscillation.

Ultra-precision grinding is crucial for manufacturing high-end optics and molds, while the unbalanced wheel vibration is inevitable and becomes even more critical in surface generation, which resulted in undesired waviness and micro-texture on the ground surface. In this paper, to understand and control the micro-texture generation, a theoretical model has been developed to predict the deterministic surface micro-texture generation resulted from unbalanced tool vibration in ultra-precision grinding, in which the overlap trajectories of grinding wheel with an arc cutting edge were analyzed and calculated. The simulation work was performed and a double phase mechanism involved in deterministic textural pattern and structure has been revealed. Both theoretical and experimental results proved that phase shift is an important factor to determine micro-texture evolution in the ultra-precision grinding process. On this basis, a novel tool path strategy has been proposed to fabricate deterministic micro-structure by coordinating oscillation motion of the grinding wheel and phase shift control, in which a rhombus-shaped micro-structure array can be generated. A small adjustment for the phase shift was conducted and it was found that the more complex micro-texture with different textural patterns and micro-structure can be machined. The results indicated that the phase control for the tool path planning is an effective method to fabricate flexible and tunable micro-texture surfaces in ultra-precision grinding.

Shenmai Injection Alleviates Acute Lung Injury in a Severe Acute Pancreatitis Rat Model via Heme Oxygenase-1 Upregulation.

BACKGROUND: One of the serious complications of severe acute pancreatitis (SAP) is acute lung injury (ALI). Suppressing inflammation is a feasible treatment strategy for SAP-induced ALI. Shenmai injection (SMI), which is a Traditional Chinese Medicine (TCM treatment, can suppress inflammation. Therefore, this study used an established SAP rat model to determine the effect of SMI on ALI induced by SAP. METHODS: A total of 40 male Sprague-Dawley (SD) rats were assigned to one of four groups: the SAP group, the sham surgery (SS) group, the SAP + SMI group and the SAP + SMI + zinc protoporphyrin (ZnPP) group. Rats in the SAP group were intravenously injected with 1.6 ml/kg saline 30 minutes after induction of SAP models, rats in the SAP + SMI group were intravenously injected with 1.6 ml/kg SMI, while rats in the SAP + SMI + ZnPP group were intravenously injected with 1.6 ml/kg SMI and 30 mg/kg ZnPP via intraperitoneal injection. The rates were sacrificed 24 hours after SAP induction. Excised lung tissues were histologically examined, protein concentration in bronchoalveolar lavage fluid (BALF) was measured and lung wet-to-dry (W/D) weight ratio was calculated. The protein and mRNA levels of tumor necrosis factor (TNF)-α, heme oxygenase (HO)-1 and interleukin (IL)-10 in blood and tissue samples were measured. RESULTS: SMI treatment attenuated SAP-induced ALI as evidenced by lower lung damage scores compared with the untreated SAP group (P < .05). SMI also abolished the SAP-induced rise in BALF and W/D ratio protein concentrations (P < .05). Moreover, SMI treatment increased HO-1 and IL-10 levels but decreased TNF-α levels in serum and tissue samples (P < .05). However, inhibition of HO-1 expression by ZnPP led to significant inhibition of all the changes. CONCLUSION: SMI can alleviate SAP-induced ALI through HO-1 upregulation.

Curvature effect on surface topography and uniform scallop height control in normal grinding of optical curved surface considering wheel vibration.

High-precision optical components with complex shapes or microstructures have been extensively used in numerous fields such as biomedicine, energy and aerospace. In order to accurately achieve the specific functions of the components, the form accuracy and uniform surface quality need to reach an ever-high level. To achieve this, ultra-precision normal grinding is used for machining various types of complex optical surfaces. However, the intricate variation of the workpiece curvature and grinding wheel vibration gives rise to great challenges to obtain higher precision and uniform surface conditions. In this study, the influence of curvature on surface topography generation has been investigated and a novel model of scallop height has been developed for surface topography generation in the normal grinding of the curved surface. In addition, the relative influence of the curvature is analyzed experimentally, in which the micro-waviness generation as a consequence of the unbalanced vibration of the grinding wheel is modeled and validated by experiments. Finally, the micro sinusoidal array with the setting value for scallop height is achieved by controlling the feed speed, which is determined by the local curvature of surface profile. The results indicated that the curvature variation posed a significant effect on surface uniformity and the model is valid to achieve surface scallop height control in the normal grinding effectively.

Intravenous immunoglobulin-based adjuvant therapy for severe COVID-19: a single-center retrospective cohort study.

OBJECTIVE: Coronavirus disease 2019 (COVID-19) is a major challenge facing the world. Certain guidelines issued by National Health Commission of the People's Repubilic of China recommend intravenous immunoglobulin (IVIG) for adjuvant treatment of COVID-19. However, there is a lack of clinical evidence to support the use of IVIG. METHODS: This single-center retrospective cohort study included all adult patients with laboratory-confirmed severe COVID-19 in the Respiratory and Critical Care Unit of Dabie Mountain Regional Medical Center, China. Patient information, including demographic data, laboratory indicators, the use of glucocorticoids and IVIG, hospital mortality, the application of mechanical ventilation, and the length of hospital stay was collected. The primary outcome was the composite end point, including death and the use of mechanical ventilation. The secondary outcome was the length of hospital stay. RESULTS: Of the 285 patients with confirmed COVID-19, 113 severely ill patients were included in this study. Compared to the non-IVIG group, more patients in the IVIG group reached the composite end point [12 (25.5%) vs 5 (7.6%), P = 0.008] and had longer hospital stay periods [23.0 (19.0-31.0) vs 16.0 (13.8-22.0), P < 0.001]. After adjusting for confounding factors, differences in primary outcomes between the two groups were not statistically significant (P = 0.167), however, patients in the IVIG group had longer hospital stay periods (P = 0.041). CONCLUSION: Adjuvant therapy with IVIG did not improve in-hospital mortality rates or the need for mechanical ventilation in severe COVID-19 patients. Our study does not support the use of immunoglobulin in patients with severe COVID-19 patients.

Method to improve the surface shape of BK7 glass in full-aperture polishing.

Full aperture polishing is a significant process to fabricate optical workpieces with nano figure precision. It has the characteristics of excellent full spectrum uniform removal ability, fast convergence speed, high machining accuracy, and low production cost, which makes it the first choice for the processing of large-aperture optical elements. However, with BK7 glass it is difficult to achieve deterministic processing due to its large thermal expansion coefficient and other factors, and the surface shape accuracy is difficult to improve. In this paper, the thermal deformation of BK7 glass is analyzed first, and then the temperature distribution in the element is measured during full-aperture polishing. The influence of the temperature field in the optics on the accuracy of the final surface shape is analyzed, and the quantitative relationship between the temperature difference and the surface shape is established. In addition, the methods of deterministically controlling the surface shape of optics such as polishing liquid temperature control and immersion polishing are proposed. Finally, the model of quantitative control of the surface shape of optics is verified by experiments, which improve the surface shape accuracy of 600 mm BK7 optics to 0.2λ.

Shenmai Injection Upregulates Heme Oxygenase-1 to Confer Protection Against Severe Acute Pancreatitis.

BACKGROUND: To explore the mechanism of Shenmai injection (SMI) on severe acute pancreatitis (SAP) through heme oxygenase-1 (HO-1) signaling. METHODS: A total of 40 male Sprague-Dawley (SD) rats (220-260 g) were grouped into the following four categories (n = 10): SAP + SMI + Zinc protoporphyrin (ZnPP), SAP + SMI, SAP, and sham surgery groups. ZnPP is a specific inhibitor of HO-1. Four percent of sodium taurocholate (1 mL/kg) was retrogradely injected via the pancreatic duct to induce the SAP model. The SAP group rats received 1.6 mL/kg saline by intravenous injection 30 min after the induction of SAP. The SAP + SMI group rats received 1.6 mL/kg SMI by intravenous injection 30 min after the induction of SAP. The SAP + SMI + ZnPP group rats received an intravenous injection of 1.6 mL/kg SMI and intraperitoneal administration of 30 mg/kg ZnPP 30 min after the SAP induction. Twenty-four hours after the SAP induction, blood samples were collected for the measurement of amylase, lipase, creatinine, myeloperoxidase, interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and HO-1 level, while tissue specimens were harvested for the determination of HO-1, TNF-α, and IL-10 mRNA level. Meanwhile, histopathological changes in organs (pancreas, lung, and kidney) were stored. RESULTS: The serum concentration of amylase, lipase, creatinine, and myeloperoxidase was higher in the SAP group than in the SAP + SMI group. Treatment with SMI increased HO-1 and IL-10 level and reduced TNF-α level in serum and tissues compared to the SAP group (P < 0.05). Treatment with SMI abolished the organ-damaging effects of SAP (P < 0.05). Furthermore, suppression of HO-1 expression by ZnPP canceled the aforementioned effects. CONCLUSIONS: SMI confers protection against the SAP-induced systemic inflammatory response and multiple organs damage via HO-1 upregulation.

High-Contrast SEM Imaging of Supported Few-Layer Graphene for Differentiating Distinct Layers and Resolving Fine Features: There is Plenty of Room at the Bottom.

For supported graphene, reliable differentiation and clear visualization of distinct graphene layers and fine features such as wrinkles are essential for revealing the structure-property relationships for graphene and graphene-based devices. Scanning electron microscopy (SEM) has been frequently used for this purpose where high-quality image contrast is critical. However, it is surprising that the effect of key imaging parameters on the image contrast has been seriously undermined by the graphene community. Here, superior image contrast of secondary electron (SE) images for few-layer graphene supported on SiC and SiO2 /Si is realized through simultaneously tuning two key parameters-acceleration voltage (Vacc ) and working distance (WD). The overlooked role of WD in characterizing graphene is highlighted and clearly demonstrated. A unified model of Vacc and WD dependence of three types of SE collected by the standard side-attached Everhart-Thornley (E-T) SE detector is conceptually developed for mechanistically understanding the improved mass thickness contrast for supported few-layer graphene. The findings reported here will have important implications for effective characterizations of atomically thick 2D materials and devices.

Kinematic model for material removal distribution and surface figure in full-aperture polishing.

Full-aperture polishing is a significant process for fabricating large ultra-precision optic flats. The surface figure is one of the key specifications required of the optic flats, which is determined by the material removal distribution during polishing. To date, the most frequently referred to equation, the Preston equation, only provides a solution for qualitative calculation of material removal of a single point on the optic surface. In this study, we present a kinematic model for deterministic calculation of the removal amount at every local optic position. The model is based on the sliding track of each local optic position on the lap, and it incorporates local pressure and most key kinematic parameters and considers the effect of the lap grooves. With this model, we analyzed the impacts of various kinematic parameters and groove features on the distribution of the removal amount in terms of sliding distance, assuming a uniform pressure distribution at the lap/optic interface. Several polishing experiments have been carried out in which the model is validated.

Investigation on surface/subsurface deformation mechanism and mechanical properties of GGG single crystal induced by nanoindentation.

In this paper, nanoindentation tests of GGG single crystal are performed on an Agilent G200 nanoindenter. The surface morphology and subsurface deformation mechanism induced by the nanoindentation are analyzed by a scanning electron microscope and a transmission electron microscope (TEM), respectively. The ductile deformation mechanism of GGG single crystal induced by the nanoindentation is a combination of "polycrystalline nanocrystallites" and "amorphous transformation." In addition, the relationships between the normal force and elastic recovery, microhardness, elastic modulus, and fracture toughness of GGG single crystal are researched. Due to the size effect caused by the tip radius of the indenter, the elastic recovery rate and fracture toughness decrease first and then tend to be stable as the normal force increases, while the microhardness and elastic modulus increase first and then decrease to be stable as the normal force increases. The stress-strain curve of GGG single crystal is developed by using the nanoindentation test with a spherical indenter. When GGG single crystal deforms from the elastic regime into the ductile regime, the original single crystal is changed into "polycrystalline nanocrystallites" and "amorphous transformation" structures verified by TEM. Therefore, the material strength decreases, which results in a discontinuity of the stress-strain curve for GGG single crystal.

Protective effects of heme oxygenase-1 against severe acute pancreatitis via inhibition of tumor necrosis factor-α and augmentation of interleukin-10.

BACKGROUND: Heme oxygenase-1 (HO-1) is an inducible defense gene which plays a significant role in inflammation. HO-1 protects cells and tissues through the mechanism of anti-oxidation, maintaining microcirculation and anti-inflammation. The aim of the current study is to investigate the role of HO-1 on systemic inflammatory response in severe acute pancreatitis (SAP). METHODS: Forty male Sprague-Dawley (SD) rats were randomly assigned into four groups: control group (n = 10); SAP group (n = 10), SAP model was induced by retrograde injection of 3% sodium taurocholate through pancreatic duct; HO-1 stimulation group (n = 10), SD rats were injected 75 µg/kg hemin intraperitoneally 30 min after induction of SAP; HO-1 inhibition group (n = 10), SD rats were injected 20 µg/kg Zinc porphyrin (Zn-PP) intraperitoneally 30 min after induction of SAP. After 24 h of SAP establishment, tissues were collected for HO-1, tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) mRNA expression, and blood samples were collected for cytokines and biochemical measurements. Meanwhile, the histopathological changes of pancreas and liver tissues were observed. RESULTS: The expression of HO-1 mRNA and protein were significantly induced by SAP in rat pancreas and liver. Hemin treatment significantly decreased oxidative stress and TNF-α in plasma and tissues, while the IL-10 was significantly increased. Pancreas and liver injury induced by SAP was markedly attenuated by Hemin treatment. Moreover, inhibition of HO-1 expression by Zn-PP administration aggravated the injury caused by SAP. CONCLUSIONS: Induction of HO-1 in early SAP may modulate systemic inflammatory response and prevent pancreas and nearby organs such as liver injury through inhibition of TNF-α and augmentation of IL-10.

Cooperative Localization for Multi-AUVs Based on GM-PHD Filters and Information Entropy Theory.

Cooperative localization (CL) is considered a promising method for underwater localization with respect to multiple autonomous underwater vehicles (multi-AUVs). In this paper, we proposed a CL algorithm based on information entropy theory and the probability hypothesis density (PHD) filter, aiming to enhance the global localization accuracy of the follower. In the proposed framework, the follower carries lower cost navigation systems, whereas the leaders carry better ones. Meanwhile, the leaders acquire the followers' observations, including both measurements and clutter. Then, the PHD filters are utilized on the leaders and the results are communicated to the followers. The followers then perform weighted summation based on all received messages and obtain a final positioning result. Based on the information entropy theory and the PHD filter, the follower is able to acquire a precise knowledge of its position.

A Study on the Model of Detecting the Variation of Geomagnetic Intensity Based on an Adapted Motion Strategy.

By simulating the geomagnetic fields and analyzing thevariation of intensities, this paper presents a model for calculating the objective function ofan Autonomous Underwater Vehicle (AUV)geomagnetic navigation task. By investigating the biologically inspired strategies, the AUV successfullyreachesthe destination duringgeomagnetic navigation without using the priori geomagnetic map. Similar to the pattern of a flatworm, the proposed algorithm relies on a motion pattern to trigger a local searching strategy by detecting the real-time geomagnetic intensity. An adapted strategy is then implemented, which is biased on the specific target. The results show thereliabilityandeffectivenessofthe proposed algorithm.

Graph-Based Cooperative Localization Using Symmetric Measurement Equations.

Precise localization is a key requirement for the success of highly assisted or autonomous vehicles. The diminishing cost of hardware has resulted in a proliferation of the number of sensors in the environment. Cooperative localization (CL) presents itself as a feasible and effective solution for localizing the ego-vehicle and its neighboring vehicles. However, one of the major challenges to fully realize the effective use of infrastructure sensors for jointly estimating the state of a vehicle in cooperative vehicle-infrastructure localization is an effective data association. In this paper, we propose a method which implements symmetric measurement equations within factor graphs in order to overcome the data association challenge with a reduced bandwidth overhead. Simulated results demonstrate the benefits of the proposed approach in comparison with our previously proposed approach of topology factors.

Random Finite Set Based Bayesian Filtering with OpenCL in a Heterogeneous Platform.

While most filtering approaches based on random finite sets have focused on improving performance, in this paper, we argue that computation times are very important in order to enable real-time applications such as pedestrian detection. Towards this goal, this paper investigates the use of OpenCL to accelerate the computation of random finite set-based Bayesian filtering in a heterogeneous system. In detail, we developed an efficient and fully-functional pedestrian-tracking system implementation, which can run under real-time constraints, meanwhile offering decent tracking accuracy. An extensive evaluation analysis was carried out to ensure the fulfillment of sufficient accuracy requirements. This was followed by extensive profiling analysis to spot the potential bottlenecks in terms of execution performance, which were then targeted to come up with an OpenCL accelerated application. Video-throughput improvements from roughly 15 fps to 100 fps (6×) were observed on average while processing typical MOT benchmark videos. Moreover, the worst-case frame processing yielded an 18× advantage from nearly 2 fps to 36 fps, thereby comfortably meeting the real-time constraints. Our implementation is released as open-source code.

Surface deformation and friction characteristic of nano scratch at ductile-removal regime for optical glass BK7.

Nano scratch for optical glass BK7 based on the ductile-removal regime was carried out, and the influence rule of scratch parameters on surface deformation and friction characteristic was analyzed. Experimental results showed that, with increase of normal force, the deformation of burrs in the edge of the scratch was more obvious, and with increase of the scratch velocity, the deformation of micro-fracture and burrs in the edge of the scratch was more obvious similarly. The residual depth of the scratch was measured by atomic force microscope. The experimental results also showed that, with increase of normal force, the residual depth of the scratch increased linearly while the elastic recovery rate decreased. Furthermore, with increase of scratch velocity, the residual depth of the scratch decreased while the elastic recovery rate increased. The scratch process of the Berkovich indenter was divided into the cutting process of many large negative rake faces based on the improved cutting model, and the friction characteristic of the Berkovich indenter and the workpiece was analyzed. The analysis showed that the coefficient of friction increased and then tended to be stable with the increase of normal force. Meanwhile, the coefficient of friction decreased with the increase of scratch velocity, and the coefficients, k ln(v) and µ0, were introduced to improve the original formula of friction coefficient.

Vehicle Detection Based on Probability Hypothesis Density Filter.

In the past decade, the developments of vehicle detection have been significantly improved. By utilizing cameras, vehicles can be detected in the Regions of Interest (ROI) in complex environments. However, vision techniques often suffer from false positives and limited field of view. In this paper, a LiDAR based vehicle detection approach is proposed by using the Probability Hypothesis Density (PHD) filter. The proposed approach consists of two phases: the hypothesis generation phase to detect potential objects and the hypothesis verification phase to classify objects. The performance of the proposed approach is evaluated in complex scenarios, compared with the state-of-the-art.

Systematic Error Modeling and Bias Estimation.

This paper analyzes the statistic properties of the systematic error in terms of range and bearing during the transformation process. Furthermore, we rely on a weighted nonlinear least square method to calculate the biases based on the proposed models. The results show the high performance of the proposed approach for error modeling and bias estimation.

Relationship between asperity-mediated surface forces and topography alteration of silica microspheres sliding on mica, sapphire, and glass substrates under ambient conditions: atomic force microscopy and theoretical studies.

Contact geometry significantly influences adhesive force measurements and modeling for adhesion/friction studies where an AFM colloidal probe technique has been extensively employed. Here we present a systematic study on the topography alteration of silica microspheres sliding on mica, sapphire, and glass substrates under ambient conditions at a relative humidity of 30-55% and the consequential adhesion behaviors of worn microspheres through AFM direct force measurements and theoretical modeling. The wearing of microspheres creates a truncated platform, which is largest for sliding on glass substrates. On the platform are nanoasperities consisting of wear debris and airborne particulate contaminants. Variations in adhesive forces with sliding time and testing modes as well as the effect of surface roughness of substrates are explained within the theoretical framework of nanoasperity-mediated capillary and van der Waals forces. The drawbacks of the present reverse-imaging method for microsphere topography examination, and numerous sources of errors associated with the extraction of key parameters for force modeling, are discussed in detail. The results will also have important implications for more reliable AFM colloidal probe technique and its application in adhesion and tribological studies.

Research on the material removal in the polishing of potassium dihydrogen phosphate crystals based on deliquescent action.

Through the polishing experiments of potassium dihydrogen phosphate (KDP) crystals based on deliquescent action, the effect of several major factors, including crystal's initial surface state, polishing time, and revolution of polishing plate, on material removal was researched. Under certain experimental conditions, the rules of material removal were reached, and experimental results are discussed, which lays the foundation for popularization and application of polishing technology for KDP crystals based on deliquescent action.

Multiple vehicle cooperative localization with spatial registration based on a probability hypothesis density filter.

This paper studies the problem of multiple vehicle cooperative localization with spatial registration in the formulation of the probability hypothesis density (PHD) filter. Assuming vehicles are equipped with proprioceptive and exteroceptive sensors (with biases) to cooperatively localize positions, a simultaneous solution for joint spatial registration and state estimation is proposed. For this, we rely on the sequential Monte Carlo implementation of the PHD filtering. Compared to other methods, the concept of multiple vehicle cooperative localization with spatial registration is first proposed under Random Finite Set Theory. In addition, the proposed solution also addresses the challenges for multiple vehicle cooperative localization, e.g., the communication bandwidth issue and data association uncertainty. The simulation result demonstrates its reliability and feasibility in large-scale environments.