Bilateral Elimination Rule-Based Finite Class Bayesian Inference System for Circular and Linear Walking Prediction.

OBJECTIVE: The prediction of upcoming circular walking during linear walking is important for the usability and safety of the interaction between a lower limb assistive device and the wearer. This study aims to build a bilateral elimination rule-based finite class Bayesian inference system (BER-FC-BesIS) with the ability to predict the transition between circular walking and linear walking using inertial measurement units. METHODS: Bilateral motion data of the human body were used to improve the recognition and prediction accuracy of BER-FC-BesIS. RESULTS: The mean predicted time of BER-FC-BesIS in predicting the left and right lower limbs' upcoming steady walking activities is 119.32 ± 9.71 ms and 113.75 ± 11.83 ms, respectively. The mean time differences between the predicted time and the real time of BER-FC-BesIS in the left and right lower limbs' prediction are 14.22 ± 3.74 ms and 13.59 ± 4.92 ms, respectively. The prediction accuracy of BER-FC-BesIS is 93.98%. CONCLUSION: Upcoming steady walking activities (e.g., linear walking and circular walking) can be accurately predicted by BER-FC-BesIS innovatively. SIGNIFICANCE: This study could be helpful and instructional to improve the lower limb assistive devices' capabilities of walking activity prediction with emphasis on non-linear walking activities in daily living.

The L-shaped Zygomatic Reduction with Oblique or Vertical Resection: Which One is the Optimal Choice?

BACKGROUND: This study aims to investigate the optimal surgical techniques in reduction malarplasty by comparing the difference between the L-shaped osteotomy with vertical and oblique bone resection. METHODS: One hundred and twenty patients who visited our department for L-shaped osteotomy with either vertical (Group Ⅰ) or oblique bone resection (Group Ⅱ) from 2015 to 2021 were retrospectively reviewed. The preoperative and postoperative spiral computed tomography (CT) data were analyzed. The preoperative CT data was also used to simulate the virtual and model surgery. RESULTS: The results showed that a broken-bridge-like structure with a bony gap of 2.86±1.03 mm at the zygomatic arch root was observed in Group Ⅰ, and a mortice and tenon joint structure with a bone overlap of 2.28±0.58 mm was formed in Group Ⅱ. The zygoma in Group Ⅰ displaced significantly in the vertical direction and horizontal direction during the follow-up. Simultaneously, the incidence of complications was higher in Group Ⅰ. In the mechanism analysis through virtual and model surgery, the zygomatic segment was shifted anteriorly and inferiorly in Group Ⅰ, and a bony gap was detected at the zygomatic arch root. Conversely, a superior and posterior movement was performed in Group Ⅱ and it maintained the zygomatic complex integral with bone overlap at the zygomatic arch root upon repositioning. CONCLUSION: This study suggested that L-shaped osteotomy with oblique bone resection could be the optimal choice for reducing zygomatic prominence.

The accuracy of virtual surgical planning assisted management for L-shaped reduction malarplasty: A retrospective study.

This study aims to evaluate the accuracy of L-shaped reduction malarplasty with bone setback or resection on the zygoma and the mortice and tenon joint structure on the zygomatic arch under the guidance of virtual surgical planning (VSP). Adult patients with zygomatic protrusion or hypertrophy were enrolled and divided. L-shaped reduction malarplasty with or without bone resection and with the mortice and tenon joint structure on the zygomatic arch was conducted either by digital procedures comprising VSP and three-dimensional (3D) printing titanium templates (Group I) or by conventional methods (Group II). Positions of representative landmarks and superimposition models were analyzed by 3D cephalometry. Satisfaction rate and incidences of clinical complications were compared as well. Satisfactory reduction of zygomatic protrusion or hypertrophy was recognized among all 78 patients. Improved symmetry and great surgical accuracy were observed according to the cephalometry analyses. The bone segment movement of virtual plans and actual results in Group I were measured and showed no obvious difference for the inward movement (5.42 ± 0.98 mm vs. 5.33± 0.93 mm, P = 0.6906) and the sagittal overlap (4.77 ± 1.32 mm vs. 4.87± 1.21 mm, P = 0.7386) at the zygoma roots, along with the step length at the long-arm of the L-shaped osteotomy line (2.43 ± 1.11 mm vs. 2.39± 0.89 mm, P = 0.8665). The high resemblance between virtual plans and actual results was depicted via superimposition models. Meanwhile, a higher satisfaction rate (28 in 36, 78% vs. 20 in 42, 48%) and a lower incidence rate of complications (11 in 36, 31% vs. 21 in 42, 50%) were found in Group I. Within the limitations of the study it seems that the application of VSP in reduction malarplasty could significantly contribute to better surgical accuracy and reduced difficulties in the operation, which would be beneficial to patients with zygoma hypertrophy or prominence.

Interface Stabilization in Adhesion Caused by Elastohydrodynamic Deformation.

Interfacial instabilities are common phenomena observed during adhesion measurements involving viscoelastic polymers or fluids. Typical probe-tack adhesion measurements with soft adhesives are conducted with rigid probes. However, in many settings, such as for medical applications, adhesives make and break contact from soft surfaces such as skin. Here we study how detachment from soft probes alters the debonding mechanism of a model viscoelastic polymer film. We demonstrate that detachment from a soft probe suppresses Saffman-Taylor instabilities commonly encountered in adhesion. We suggest the mechanism for interface stabilization is elastohydrodynamic deformation of the probe and propose a scaling for the onset of stabilization.

Out-of-contact peeling caused by elastohydrodynamic deformation during viscous adhesion.

We report on viscous adhesion measurements conducted in sphere-plane geometry between a rigid sphere and soft surfaces submerged in silicone oils. Increasing the surface compliance leads to a decrease in the adhesive strength due to elastohydrodynamic deformation of the soft surface during debonding. The force-displacement and fluid film thickness-time data are compared to an elastohydrodynamic model that incorporates the force measuring spring and finds good agreement between the model and data. We calculate the pressure distribution in the fluid and find that, in contrast to debonding from rigid surfaces, the pressure drop is non-monotonic and includes the presence of stagnation points within the fluid film when a soft surface is present. In addition, viscous adhesion in the presence of a soft surface leads to a debonding process that occurs via a peeling front (located at a stagnation point), even in the absence of solid-solid contact. As a result of mass conservation, the elastohydrodynamic deformation of the soft surface during detachment leads to surfaces that come closer as the surfaces are separated. During detachment, there is a region with fluid drainage between the centerpoint and the stagnation point, while there is fluid infusion further out. Understanding and harnessing the coupling between lubrication pressure, elasticity, and surface interactions provides material design strategies for applications such as adhesives, coatings, microsensors, and biomaterials.

Three-dimensional analysis of zygomatic change after L-shaped reduction malarplasty with bone setback or resection.

PURPOSE: Reduction malarplasty is one of the most popular procedures for esthetic facial contouring in East Asians. The retrospective observational study aimed to analyze the association between the zygomatic change and bone setback or resection to propose quantitative guidance for L-shaped reduction malarplasty based on computed tomographic (CT) images. METHODS: A retrospective observational study was conducted on patients who underwent L-shaped reduction malarplasty with bone resection (Group I) or without bone resection (Group II). The amount of bone setback and resection was calculated. The unilateral width changes of the anterior, middle, and posterior zygomatic regions as well as zygomatic protrusion change were also evaluated. Pearson correlation analysis and linear regression analysis were used to analyze the relationship between the bone setback or resection and the zygomatic changes. RESULTS: Eighty patients who underwent L-shaped reduction malarplasty were included in this study. Significant correlation was observed between the bone setback or resection and the change of anterior, and middle zygomatic width as well as protrusion in both the two groups (P < .001). The correlation between bone setback or resection and the posterior zygomatic width change was not significant (P ＞.05). CONCLUSION: The bone setback or resection of L-shaped reduction malarplasty lead to the anterior and middle zygomatic width and zygomatic protrusion changes. Furthermore, the linear regression equation can be referenced as a guidance for a preoperative surgical plan.

Optimal design and development of a fast steering robot inspired by scallops.

The improvement of the steering performance of jet robots is challenging due to single inflexible jet aperture. Scallops provide a potential solution with hard shells and a double-hole jet propulsion, which are expected to achieve fast steering movement under water. Inspired by scallops, a bionic propulsion dynamic mesh is proposed in this article, and a three-dimensional computational model of scallops is established. We further calculated the scallop propulsion mechanism under the swing of shells with different shapes. The coupling of simultaneous swing of two shells and their coupling with velum are presented, revealing the unique movement mechanism of Bivalvia. Based on this, the advantages of the double-hole jet propulsion are applied to develop a scallop robot with excellent steering capabilities. Experiments are conducted to verify the steering performance of the scallop robot.

The importance of the mortice and tenon joint on the zygomatic arch in reduction malarplasty-a retrospective study.

The aim of this study was to compare two kinds of reduction malarplasty in terms of their bony consolidation. Patients that underwent reduction malarplasty were reviewed retrospectively. The medial movement of the zygomatic body and the zygomatic arch as well as the complications and satisfaction of patients were investigated. The surgical procedure entailed a classical or modified L-shaped osteotomy through intraoral and sideburn approaches. Two groups were distinguished, those for whom a mortice and tenon joint was formed on the zygomatic arch (Group I), and those that formed end-to-end bone contact (Group II). All the cases in Group I showed an improved facial contour with sufficient bone contact. A larger medial movement of the zygomatic arch was observed in Group I (4.54 ± 0.41 mm) than in Group II (2.72 ± 0.29 mm) (P = 0.016). More bone malunion was observed in six cases of Group II (P = 0.030) and four required a second operation. In conclusion, this study indicates that the mortice and tenon approach is preferable when the priority is bony consolidation.

On-road mileage-based emission factors of gaseous pollutants from bi-fuel taxi fleets in China: The influence of fuel type, vehicle speed, and accumulated mileage.

Urban taxis tend to be high mileage vehicles, and therefore potentially a significant contributor to local air pollution. To investigate the on-road emissions of gaseous air pollutants from urban taxi fleets, the mileage-based emission factors (EFs) for 20 gasoline/CNG bi-fuel taxis in China were measured using the in situ monitoring system. It was found that shifting the taxis' fuel from gasoline to CNG could cause significant emissions reduction in CO, slight drop in HC and small increase in NOx. With the fuel shift from China-VI gasoline to GB 18047-2017 CNG, approximately 82% reduction in CO, 14% reduction in HC and about 14% more NOx was observed. With fuel shift from China-III gasoline to GB 18047-2000 CNG, the reductions were 65%, 6% and 11%, respectively. When the China-VI gasoline-fueled taxis travel at higher speed (60 km/h or higher), the vehicles emit approxiamtly ten times more CO than that at lower speed (20-50 km/h). The mileage-based NOxEFs was strongly and positively related to the vehicles' speed for the taxis fueled by China-VI gasoline and GB 18047-2017 CNG. The ratio of NOx and HC emissions from gasoline-fueled taxis is lower than that from CNG-fueled taxis. Considerable reductions of the mileage-based EFs of CO, HC, and NOx from China-VI gasoline- and GB 18047-2017 CNG-fueled bi-fuel taxis were recorded. The taxi vehicles with higher accumulated mileage (greater than 200,000 km) were found with higher CO and HC emissions, due to the deterioration of vehicle engine performance and the exhaust catalyst system.

Development of a biomimetic scallop robot capable of jet propulsion.

Inspired by a scallop's strong underwater propulsion mechanism, we designed and prototyped a scallop robot capable of clapping and swimming. In this work, an artificial velum was used to work as a check valve to stimulate the robot's swimming. A couple of supporting plates were fixed on the robot shells to achieve the modulation of clapping process of the shells. The scallop robot can move at a maximum average and instantaneous speed of 3.4 and 4.65 body lengths per second, respectively. The effect of the supporting plates, the artificial velum, as well as the clapping frequency and amplitude on the swimming performance of the scallop robot was also experimentally evaluated. By tuning the sizes of the jet apertures, the scallop robot is capable of achieving high mobility actions such as turning. We also obtained the aperture ratio with the corresponding turning radius. This scallop robot provides a new propulsion mechanism in underwater bionic robots; it is also of help to understand the swimming principle of scallops in terms of jet propulsion and clapping motion.

Morphology of soft and rough contact via fluid drainage.

The dynamic of contact formation between soft materials immersed in a fluid is accompanied by fluid drainage and elastic deformation. As a result, controlling the coupling between lubrication pressure and elasticity provides strategies to design materials with reversible and dynamic adhesion to wet or flooded surfaces. We characterize the elastic deformation of a soft coating with nanometer-scale roughness as it approaches and contacts a rigid surface in a fluid environment. The lubrication pressure during the approach causes elastic deformation and prevents contact formation. We observe deformation profiles that are drastically different from those observed for elastic half-space when the thickness of the soft coating is comparable to the hydrodynamic radius. In contrast, we show that surface roughness favors fluid drainage without altering the elastic deformation. As a result, the coupling between elasticity and slip (caused by surface roughness) can lead to trapped fluid pockets in the contact region.

A multifunctional force microscope for soft matter with in situ imaging.

We present the multifunctional force microscope (MFM), a normal and lateral force-measuring instrument with in situ imaging. In the MFM, forces are calculated from the normal and lateral deflection of a cantilever as measured via fiber optic sensors. The motion of the cantilever is controlled normally by a linear micro-translation stage and a piezoelectric actuator, while the lateral motion of the sample is controlled by another linear micro-translation stage. The micro-translation stages allow for travel distances that span 25 mm with a minimum step size of 50 nm, while the piezo has a minimum step size of 0.2 nm, but a 100 µm maximum range. Custom-designed cantilevers allow for the forces to be measured over 4 orders of magnitude (from 50 µN to 1 N). We perform probe tack, friction, and hydrodynamic drainage experiments to demonstrate the sensitivity, versatility, and measurable force range of the instrument.

Elastic deformation of soft coatings due to lubrication forces.

Elastic deformation of rigid materials with soft coatings (stratified materials) due to lubrication forces can alter the interpretation of dynamic surface forces measurements and prevent contact formation between approaching surfaces. Understanding the role of elastic deformation on the process of fluid drainage is necessary, in particular for the case where one (or both) of the interacting materials consists of a rigid substrate with a soft coating. We combine lubrication theory and solid linear elasticity to describe the dynamic of fluid drainage past a compliant stratified boundary. The analysis presented covers the full range of coating thicknesses, from an elastic foundation to a half-space for an incompressible coating. We decouple the individual contributions of the coating thickness and material properties on the elastic deformation, hydrodynamic forces, and fluid film thickness. We obtain a simple expression for the shift in contact position during force measurements that is valid for many experimental conditions. We compare directly the effect of stratification on the out-of-contact deformation to the well-known effect of stratification on indentation. We show that corrections developed for stratification in contact mechanics are not applicable to elastohydrodynamic deformation. Finally, we provide generalized contour maps that can be employed directly to estimate the elastic deformation present in most dynamic surface force measurements.

Out-of-Contact Elastohydrodynamic Deformation due to Lubrication Forces.

We characterize the spatiotemporal deformation of an elastic film during the radial drainage of fluid from a narrowing gap. Elastic deformation of the film takes the form of a dimple and prevents full contact to be reached. With a thinner elastic film the stress becomes increasingly supported by the underlying rigid substrate and the dimple formation is suppressed, which allows the surfaces to reach full contact. We highlight the lag due to viscoelasticity on the surface profiles, and that for a given fluid film thickness deformation leads to stronger hydrodynamic forces than for rigid surfaces.