Search Results (14)

Due to the rise of gigascale antenna arrays considered to implement long-range wireless power transfer (WPT), there is a need for a scalable high-efficiency adaptive dynamic beam focusing method. Several methods have been proposed, including methods requiring position information of the receiver, use of pilot signals or channel sounding, and feedback-based approaches. The latter has the potential to achieve maximum WPT efficiency due to use of feedback between the rectenna target and the transmitter array. In this paper, we present an overview of the different feedback-based long-range WPT methods that have been proposed. We also compare their performance in terms of convergence time, complexity of implementation, and steady-state efficiency through an electromagnetic simulation, whose results are incorporated into a time-domain simulation model. The results show that methods that measure channel state information (CSI) and the both-sides retrodirective system can achieve high efficiency with less convergence time but with added implementation complexity. Full article

Roadside vegetation helps to retain air pollutants emitted by road traffic. On the other hand, its presence makes it difficult to ventilate street canyons. The paper examines the influence of vegetation on the dispersion of air pollution generated by road traffic, using the example of two street canyons—both-sided and one-sided street canyons. The study was conducted taking into account the actual emission conditions occurring on the analyzed road sections estimated using the HBEFA methodology. Subsequently, a three-dimensional pollution dispersion model named MISKAM was employed to simulate the air pollutant dispersion conditions in the analyzed street canyons. The modelling results were compared with the measurement data from air quality monitoring stations located in these canyons. The obtained results indicated that the presence of vegetation can significantly impact on the air dispersion of traffic-related exhaust and non-exhaust emissions. The impact of vegetation is more pronounced in the case of a street canyon with dense, high-rise development on both sides than in the case of a street canyon with such development on only one side. The results for the both-sided street canyon demonstrate that the discrepancy between the scenario devoid of vegetation and the scenario with vegetation was approximately 5 µg/m³ (10%) for PM₁₀ and approximately 54 µg/m³ (45%) for NO_x, with the former scenario showing lower values than the latter. Nevertheless, the scenario with the vegetation exhibited a lesser discrepancy with the air quality measurements. Vegetation functions as a natural barrier, reducing wind speed in the street canyon, which in turn limits the spread of pollutants in the air, leading to pollutant accumulation near the building walls that form the canyon. Consequently, atmospheric dispersion modelling must consider the presence of vegetation to accurately evaluate the effects of road traffic emissions on air quality in urban areas, particularly in street canyons. The results of this study may hold importance for urban planning and decision-making regarding environmental management in cities aimed at improving air quality and public health. Full article

The red soil region in southern China has become the second-largest soil erosion area after the Loess Plateau. The evolutionary trajectory of soil fungi during vegetation restoration in acidic red soil regions remains a subject of inquiry. The investigation focused on the restoration process of an ecosystem facing intense degradation in the southern regions of China by studying four distinctive vegetation types: barren land (BL), pure Pinus massoniana forest (CF), mixed coniferous (CBF), and broad-leaved forest (BF). The outcomes revealed considerable enhancements in soil properties’ attributes, evident through a gradual reduction in the bulk density of soil (SBD) and a corresponding increment in soil moisture content (MC), total nitrogen (TN), total carbon (TC), total potassium (TK), soil organic matter (SOM), and available potassium (AK) as vegetation restoration advanced. An intriguing trend emerged where the relative abundance of Ascomycota fungi displayed a declining trajectory, whereas Basidiomycota fungi exhibited an ascending trend with the progression of vegetation restoration. Specifically, broad-leaved forests exhibited a significantly greater relative abundance of Penicillium fungi compared to other stages of vegetation restoration. The diversity of soil fungal communities increased in tandem with vegetation restoration. A redundancy analysis illuminated a strong and positive relationship between the abundance of major soil fungi and soil pH, TN, and TC (key influencers of acidic red soil fungal populations). This study provided additional evidence of an elevation in ectomycorrhizal and saprophytic trophic fungi, signifying a transition that enhances the vegetation’s ability to capture water and nutrients. This, in turn, contributes to the overall enrichment and diversity of vegetation communities during the progression of restoration. Full article

Differing from the published documents on the effect of texture distributions of sliding tribo-pairs on their friction and wear properties, this study introduced eight patterns to reveal the influence of different distributions of pits on the tribological behavior of textured rolling element bearings with nylon cages under dry condition, namely: Outside-1/4 (OS1/4), Outside-1/2 (OS1/2), Outside-3/4 (OS3/4), Inside-1/4 (IS1/4), Inside-1/2 (IS1/2), Inside-3/4 (IS3/4), Bothside-1/3 (BS) and full (FP). A fiber laser marking system was used to prepare them on the raceways of the shaft washers of cylindrical roller thrust bearings (81107TN). A vertical universal wear test rig was used to obtain their coefficients of friction under an axial load of 2600 N and a rotating speed of 250 RPM, without any lubricant provided. Their wear losses and worn surfaces were characterized. The influence mechanism of different distributions on the tribological properties was also discussed. The results show that the self-lubricating performance of nylon cages can ensure the continuous operation (≥5 h) of cylindrical roller thrust bearings under dry condition. The influence of outside-distributed patterns on the friction and wear properties of bearings is significant. The friction-reducing effect and wear resistance of full textured group is improved but not the best. The friction-reducing and anti-wear behavior of OS1/2 is similar to that of FP. In this work, OS3/4 can provide the best tribological performance under self-lubricating conditions. Compared with the data of smooth bearings, its average coefficient of friction and wear loss can be reduced by 37.68% and 38.85%, respectively. This work would provide a valuable reference for the raceway design and reliability optimization of rolling element bearings. Full article

This study investigates the influence of soft stabilization splints on electromyographic patterns in masticatory and neck muscles in healthy women. A total of 70 healthy women were qualified for the research. The resting and clenching electromyographic patterns of the temporalis (TA), masseter (MM), digastric (DA), and sternocleidomastoid (SCM) muscles were measured using the BioEMG III™ apparatus. The interaction between splint application and resting muscle activity affected the results in all examined muscles except the temporalis muscle. A large effect size was observed in masseter (2.19 µV vs. 5.18 µV; p = 0.00; ES = 1.00) and digastric (1.89 µV vs. 3.17 µV; p = 0.00; ES = 1.00) both-sided RMS activity. Significant differences between the two conditions were observed in all Functional Clenching Indices (FCI) for MM, SDM, and DA muscles. All FCI values for the MM and DA muscles were significantly lower with than without the splint. We observed an increase in all activity indices due to splint application, which suggests a masseter muscle advantage during measurement. The soft stabilization splint influenced resting and functional activity in the MM, SDM, and DA muscles. During tooth clenching, a soft stabilization splint changed the involvement proportions of the temporalis and masseter muscles, transferring the main activity to the masseter muscles. Using a soft stabilization splint did not affect the symmetry of the electromyographic activity of the masticatory and neck muscles. Full article

Old structures that are made of adobe or brick walls are usually unreinforced and not designed for lateral forces. In-plane loads applied to unreinforced masonry walls (URM) are the usual cause of damage and failure of old buildings. In this research, small unreinforced brick masonry wallettes, 350 mm × 350 mm and 50 mm in thickness, are strengthened using bamboo fiber textile and plastered to the face of the walls using short bamboo fiber-reinforced geopolymer mortar. The wallettes are subjected to diagonal shear tests as described by ASTM E519 to investigate the in-plane shear performance of the strengthening method. The performances of 5 wallettes strengthened on one-side with mortar only, 5 wallettes on both-sides with mortar only, 5 wallettes with textile plastered on one-side only, and another 5 wallettes with textile plastered on both-sides, are compared to 5 control specimens without any strengthening. It is observed that the wallettes strengthened on one side and both sides with textile yield an increase in shear of about 24% and 35% in average, respectively. Failure modes show that the usual failure for URM is running bond failure and for strengthened URM is columnar failure. The implications of the results can be used in developing textile-reinforced geopolymer mortar systems to strengthen URM walls. Full article

Introduction: Our aim was to investigate the applicability of artificial intelligence in predicting obstructive sleep apnoea (OSA) and upper airway obstruction using ultrasound (US) measurements of subcutaneous adipose tissues (SAT) in the regions of the neck, chest and abdomen. Methods: One hundred patients were divided into mild (32), moderately severe-severe (32) OSA and non-OSA (36), according to the results of the polysomnography. These patients were examined using anthropometric measurements and US of SAT and drug-induced sleep endoscopy. Results: Using SAT US and anthropometric parameters, oropharyngeal obstruction could be predicted in 64% and tongue-based obstruction in 72%. In predicting oropharyngeal obstruction, BMI, abdominal and hip circumferences, submental SAT and SAT above the second intercostal space on the left were identified as essential parameters. Furthermore, tongue-based obstruction was predicted mainly by height, SAT measured 2 cm above the umbilicus and submental SAT. The OSA prediction was successful in 97% using the parameters mentioned above. Moreover, other parameters, such as US-based SAT, with SAT measured 2 cm above the umbilicus and both-sided SAT above the second intercostal spaces as the most important ones. Discussion: Based on our results, several categories of OSA can be predicted using artificial intelligence with high precision by using SAT and anthropometric parameters. Full article

In order to improve the accuracy and batch consistency of cylindrical roller machining, in this paper, a both-sides cylindrical roller machining method based on hard ceramic plate is proposed. Traditional cast iron and stainless-steel polishing plate were replaced by ceramic materials with high hardness and good wear resistance. After processing by centerless grinding, the cylindrical roller is processed by both-sides lapping and polishing using Al₂O₃ ceramic plates. The roundness, diameter and surface quality of the roller and the wear of the ceramic plate before and after machining were compared and analyzed in order to evaluate the feasibility and effectiveness of this method. After grinding for 1 h and polishing for 8 h, the average roundness of the cylindrical rollers decreased from the initial 2.3 μm to 0.32 μm, while the roundness of each roller tended to be the same. At the same time, the batch diameter deviation of cylindrical rollers was reduced from 3 μm to 1 μm, and the batch consistency was satisfactory. The machining marks produced by centerless grinding on the roller surface were completely removed, and the surface quality was significantly improved. The surface roughness after polishing reached Ra 16 nm. The upper and lower ceramic plate had certain wear, but the amount was small, having little impact on the machining results. The shape accuracy and batch consistency of the rollers after machining were satisfactory. The ceramic plate had high hardness, good wear resistance and small wear in the machining process. Additionally, it could maintain extremely high flatness for a long time. Using hard ceramic plates to process cylindrical rollers, high precision and high consistency cylindrical rollers can be obtained after machining. Full article

We investigated whether baseline foveal intraretinal fluid (IRF) localization affects the visual prognosis of branch retinal vein occlusion (BRVO). Fifty eyes from 50 patients were included in this retrospective study. We classified the eyes with IRF involving and not involving the central foveola on the vertical optical coherence tomography (OCT) image at the initial visit into both-sides (n = 17) and one-side IRF (n = 33) groups, respectively. Multiple regression analyses demonstrated that not only the baseline logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) but also the IRF localization significantly correlated with the 12-month logMAR BCVA (p = 0.04 and p = 0.001, respectively), indicating that eyes with better baseline logMAR BCVA and one-side IRF have a significantly better visual prognosis in BRVO. The foveal ellipsoid zone band was significantly more disrupted (p < 0.001) in the both-sides IRF (47.1%) group than in the one-side IRF (3.0%) group. No eyes with decimal BCVA less than 0.5 were detected in the one-side IRF group at 12 months. Thus, baseline foveal IRF localization on vertical OCT images can be considered a novel biomarker for the visual prognosis of BRVO. Full article

Single-walled carbon nanotubes (SWCNTs) and phosphorylated nanocellulose fibrils (PCNFs) were used as functional screen-print coatings on flame-retardant (FR) fabric, to improve its thermal resistance and thermophysiological comfort (wetting, water vapour and heat transmission) properties, while inducing it with electrical conductivity and UV protection. The effect of PCNF printing, followed by applying a hydrophobic polyacrylate (AP), on the same (back/B, turned outwards) or other (front/F, turned towards skin) side of the fabric, with and without the addition of 0.1–0.4 wt% SWCNTs, was studied by determining the amount of applied coating and its distribution (microscopic imaging), and measuring the fabric’s colour, air permeability, thickness, mechanical, flame and abrasion resistance properties. Due to the synergistic effect of PCNF and SWCNTs, both-sided printed fabric (front-side printed with PCNF and back-side with SWCNTs within AP) resulted in an increased heat transfer (25%) and an improved thermal resistance (shift of degradation temperature by up to 18 °C towards a higher value) and UV protection (UPF of 109) without changing the colour of the fabric. Such treatment also affected the moisture management properties with an increased water-vapour transfer (17%), reduced water uptake (39%) and asymmetric wettability due to the hydrophilic front (Contact Angle 46°) and hydrophobic back (129°) side. The increased tensile (16%) and tear (39%) strengths were also assessed in the warp direction, without worsening the abrasion resistance of the front-side. A pressure-sensing electrical conductivity (up to 4.9∙10⁻⁴ S/cm with an increase to 12.0∙10⁻⁴ S/cm at 2 bars) of the SWCNT-printed side ranks the fabric among the antistatic, electrostatic discharge (ESD) or electromagnetic interference (EMI) shielding protectives. Full article

The aim of the present study was to analyze novel functional indices of masticatory muscle activity and compare them to existing and commonly used indices in patients with temporomandibular disorders (TMDs) and healthy adults. Based on the Research Diagnostic Criteria for Temporomandibular Disorders, 78 adult women qualified for the study. Subjects were divided into two groups: diagnosed TMDs (n = 36; mean age: 23.4 ± 2.6 years) and healthy adults (n = 42; mean age: 22.4 ± 2.3 years). Measurements of the bioelectric activity of the temporalis anterior (TA), superficial masseter (MM), and anterior bellies of the digastric muscle (DA) were carried out using the BioEMG III ™. Functional Clenching (FCI) and Functional Opening (FOI) indices were obtained as the ratio of the difference between the mean muscle root mean square (RMS) potentials during functional activity, including clenching (CL) and opening (MMO), and mean muscle resting (REST) potentials. Next, based on FCI and FOI indices, the Functional Clenching Activity Index (FCAI), Functional Clenching Symmetry Index (FCSI), and Functional Opening Symmetry Index (FOSI) were obtained. The statistical analysis showed significant differences in activity index left-sided (AcI_L) and Activity index both-sided (AcI_tot) between TMDs and healthy women during rest measurements. The significant differences between both groups were noted in terms of all Functional Clenching Indices except Functional Clenching Index for MM right-sided (FCI_MM-R). In all analyzed FCI indices, the control group showed higher values compared to the TMDs. Moreover, a significant difference between TMDs and controls was observed within Functional Clenching Activity Index left-sided (FCAI_L) (14.56 vs. −0.45, p = 0.01). Both functional indices, and asymmetry (AsI) and activity (AcI) indices seem to be reliable in assessing symmetry and activity within masticatory muscles. Further studies should be performed to verify the effectiveness and suitability of the assessment of masticatory muscles using functional indices. Full article

A new Lagrangian–Eulerian method for the simulation of viscoelastic free surface flow is proposed. The approach is developed from a method in which the constitutive equation for viscoelastic stress is solved at Lagrangian nodes, which are convected by the flow, and interpolated to the Eulerian grid with radial basis functions. In the new method, a backwards-tracking methodology is employed, allowing for fixed locations for the Lagrangian nodes to be chosen a priori. The proposed method is also extended to the simulation of viscoelastic free surface flow with the volume of fluid method. No unstructured interpolation or node redistribution is required with the new approach. Furthermore, the total amount of Lagrangian nodes is significantly reduced when compared to the original Lagrangian–Eulerian method. Consequently, the method is more computationally efficient and robust. No additional stabilization technique, such as both-sides diffusion or reformulation of the constitutive equation, is necessary. A validation is performed with the analytic solution for transient and steady planar Poiseuille flow, with excellent results. Furthermore, the proposed method agrees well with numerical data from the literature for the viscoelastic die swell flow of an Oldroyd-B model. The capabilities to simulate viscoelastic free surface flow are also demonstrated through the simulation of a jet buckling case. Full article

The discontinuous joints are an essential type of natural joints. The normal force, joint persistency, and distribution exert great influences on the shear resistance of the rock joints. By simulating the uniaxial compression experiment and Brazilian test, the material parameters and the basic size standard for meshing were determined. The symmetrical discontinuous joint distribution of three types were established, the cohesive elements were inserted between the solid elements, and the numerical simulation of the shear test was conducted. The effects of joint distribution, joint continuity, and normal stress on the shear resistance of joint rock were investigated, and the law of crack evolution was analyzed. The results showed that the shear process of discontinuous joints can be divided into four stages: elastic stage, strengthening stage, plastic stage, and residual stress stage. For the scattered joint distribution, the rock bridge can provide more reinforcement for the joints, which enhances the shear resistance of the joints, the stress concentration point at the end of the joint is easy to accumulate more fracture energy, which induces the initiation of the cracks, and under the influence of unbalanced torque, the both-sided joint distribution is more likely to produce tension damage. Full article

This paper examines a persuasion game between two agents with one-sided asymmetric information, where the informed agent can reveal her private information prior to playing a Battle-of-the-Sexes coordination game. There is a close connection between the extent of information revelation and the possibility of coordination failure; while, in the absence of any coordination failure, there exist equilibria with full disclosure, in the presence of strategic uncertainty in coordination there exists an equilibrium with no information revelation. We provide a purification argument for the non-existence result, as well demonstrate that it is robust to several extensions, including both-sided asymmetric information and imprecise information revelation. Full article