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Theoretical Hertzian contact model is used to numerically study contact area of rock joints under normal deformation, stress distribution, and spatial variation of aperture during compression. Contact points suffer from the influence of shear angle and the overlap of mutual contacts. The boundary correction contact model and tangential stress effect correction model are studied to analyze mesoscopic mechanical behavior of contact changes during joint closure. Contact area, contact force, and aperture are depicted based on modified Hertzian contact model. A single-joint loading experiments with the pressure measurement film was used to explore the local stress distribution during loading process. Experimental results are compared with numerical simulation results, and there is a good agreement between the two, which verifies the accuracy of the correction. Boundary effect of adjacent contact points truly reflects the stress distribution during joint contact closure process. The correction model is of great theoretical value for analyzing mesoscopic deformation of joints and provides a reference for actual rock mass deformation and seepage through joints. Highlights: A mesoscopic contact constitutive model of rock fracture was established and its effectiveness was verified by experiments. Effective contact boundary problem in the contact process was revealed. Tangential stress effect of contact point was corrected. [ABSTRACT FROM AUTHOR]

Generally, various technologies, including waveguide below cutoff (WBC), gasket sealing, and bonding, are employed in metallic enclosures to achieve the high electromagnetic shielding performance required for EMP protection and EMC countermeasures in shielding structures or facilities. While the shielding structure or facility is properly constructed and maintained according to design specifications, its electromagnetic shielding performance can remain at the required level, effectively protecting internal electrical and electronic equipment from external electromagnetic interference. However, unintended apertures often occur during the construction or maintenance of shielding facilities, compromising their shielding performance. Therefore, it is crucial to develop technologies that prevent shielding effectiveness degradation caused by both intentional and unintentional apertures. This paper proposes a structure incorporating a composite absorber (made of dielectric and magnetic absorber) within a double metal panel of enclosure featuring an aperture, aimed at maintaining and improving the facility's shielding performance. The effectiveness of the proposed structure was validated through numerical simulation. [ABSTRACT FROM AUTHOR]

In tunnel construction, grouting is frequently used to decrease the permeability and increase the rock mass strength. One of the most challenging steps in grouting is choosing the best grout type to achieve the highest penetration and sealing efficiency in the joints. The main purpose of this study is to investigate the sealing efficiency of different grout types in the joints of a high-risk section of the Kerman water conveyance tunnel (KWCT). For this purpose, the penetrations of three types of grouts including Ordinary Portland Cement (OPC), Ultra-Fine Cement (UFC), and silica sol were determined using analytical equations. Thereafter, the sealing efficiency of each type of grout in joints with different apertures was calculated. Also, the penetration radius of each type of grout was simulated and calculated using UDEC code. Based on the results of the analytical equations, by performing the grouting for 20 min using silica sol-based grout, the joints of the high-risk section of the KWCT with apertures of 0.5–2.5 mm and 2.5–10 mm can be sealed at 'Fair' and 'Excellent' levels, respectively. Furthermore, based on the results of numerical simulations, the UFC and silica sol-based grouts can seal the joints in 'Good' and 'Excellent' levels, respectively. [ABSTRACT FROM AUTHOR]

Background: Climate change-induced geohazards are increasingly posing a critical threat to the sustained functionality and resilience of constructed infrastructures. Among these hazards, debris flows represent significant natural disasters, particularly in mountainous terrains, causing widespread property damage and loss of life globally. These phenomena involve complex interactions between solid and fluid forces, resulting in long run-out distances and high-speed flows. Predicting and monitoring debris flows is challenging due to the intricate interplay of these forces. Objective: The objective of this study is to evaluate the structural damage caused by debris flows and assess the efficacy of rigid barrier structures with passages/apertures. Method: Employing Smoothed Particle Hydrodynamics, a Lagrange-based mesh-free computational technique, the researchers simulated the impact of debris on a stiff structure. The focus was on the Rishiganga river valley in the Indian state of Uttarakhand, a region recently devastated by a debris flow that severely compromised essential infrastructure, including a hydroelectric power station. The research entailed modeling the debris flow in this specific locale and analyzing its effects on an assumed downstream rigid structure. Additionally, the study explored the outcomes of introducing a rigid barrier upstream. Results and Conclusion: Results indicated a substantial reduction in the impact on the downstream structure with the presence of an upstream rigid structure. Moreover, as the number of apertures in the upstream barrier was increased, the impact of flow on the downstream structure further diminished, because of a more streamlined flow pattern. [ABSTRACT FROM AUTHOR]

This work aims to manufacture PVDF/PDMS waterproof and moisture-permeable membranes. This objective was achieved using the electrostatic spinning in-situ polymerization method proposed by the authors. Furthermore, it was also studied how different PDMS/PVDF content significantly changed nano-fiber membrane properties such as morphology, structure and mechanical properties to improve the properties and morphology of PVDF/PDMS nano-fiber membrane. Both PVDF/DMAc solution and PDMS/THF solution had to be firstly fabricated under certain conditions. Then related equipment was utilized to characterize and test the morphology and properties of PVDF/PDMS nano-fiber membrane. Based on experiments and analysis, it's also explored how different PVDF/PDMS percent impacted on nano-fiber membrane morphology, structure, mechanical properties and waterproof and moisture permeable properties. Results showed that PVDF/PDMS membrane fabricated by electrostatic spinning in-situ polymerization method could easily manufacture PVDF/PDMS waterproof and moisture permeable membrane and that mixing solution with PVDF/PDMS mass ratio 7:3 obviously improved the morphology of waterproof and moisture permeable membrane and physical properties where PVDF/PDMS mass ratio was 7:3, which voltage was 28 kV, which injection speed was 0.5 cm/h and which receiving distance was 20 cm. Furthermore, the morphology of the textile fibrous network was very uniform such as fiber diameter: 150 nm, water contact angle(WCA): 145.7 degrees, air permeability: 3.9 mm/s, hydrostatic pressure: 132 kPa, water vapor transmission: 5115 g/m2·24 h. It was concluded that the method was analytically derived and effective. PVDF/PDMS waterproof and moisture permeable membrane and its manufacturing method could be applied to textile fields and clothing fields. [ABSTRACT FROM AUTHOR]

Abstract Background Climate change-induced geohazards are increasingly posing a critical threat to the sustained functionality and resilience of constructed infrastructures. Among these hazards, debris flows represent significant natural disasters, particularly in mountainous terrains, causing widespread property damage and loss of life globally. These phenomena involve complex interactions between solid and fluid forces, resulting in long run-out distances and high-speed flows. Predicting and monitoring debris flows is challenging due to the intricate interplay of these forces. Objective The objective of this study is to evaluate the structural damage caused by debris flows and assess the efficacy of rigid barrier structures with passages/apertures. Method Employing Smoothed Particle Hydrodynamics, a Lagrange-based mesh-free computational technique, the researchers simulated the impact of debris on a stiff structure. The focus was on the Rishiganga river valley in the Indian state of Uttarakhand, a region recently devastated by a debris flow that severely compromised essential infrastructure, including a hydroelectric power station. The research entailed modeling the debris flow in this specific locale and analyzing its effects on an assumed downstream rigid structure. Additionally, the study explored the outcomes of introducing a rigid barrier upstream. Results and Conclusion Results indicated a substantial reduction in the impact on the downstream structure with the presence of an upstream rigid structure. Moreover, as the number of apertures in the upstream barrier was increased, the impact of flow on the downstream structure further diminished, because of a more streamlined flow pattern.

During the operation of a deep geological repository in crystalline rocks for disposal of high-level radioactive waste, understanding the seepage behaviors of fractured crystalline rocks under coupled thermo-hydro-mechanical conditions is essential for the performance assessment of deep geological repositories. In this study, radial flow tests on cylindrical Beishan granite specimens with a single artificial fracture were conducted using the MTS 815 rock mechanics testing system to investigate the influence of normal stress and temperature on radial flow behaviors of rough rock fractures. Steady state method was used to measure fracture permeability, and an axial extensometer was used to measure fracture deformation during compression. A three-dimensional blue light scanner was used to characterize fracture surface morphology. Experimental results indicate that fracture permeability decreases nonlinearly with the increase of normal stress or temperature, and normal stress has a more significant influence on fracture permeability than temperature. The evolution of three-dimensional non-uniform distribution of voids under compression was numerically obtained, and the variogram was employed to quantify the non-uniform distribution characteristics of mechanical apertures. In addition, a radial flow model considering non-uniform distribution of apertures is proposed to predict the normal stress- and temperature-dependent seepage behaviors of rock fractures, and the predictions were found to be in good agreement with experimental data.

Ultrasound beams sometimes need to be steered from the edge of linear array transducers to reach the sample volume with a desired Doppler angle in vascular exams. This phantom study aims to evaluate the impact of apertures located at the array edge on peak velocity (PV) measurements. Three ultrasound scanner systems equipped with eight transducers from 3 major ultrasound vendors were tested using a flow phantom with a horizontal tube. Five spectral Doppler measurements with the aperture positioned at one edge of the array and 5 with the aperture at the center of the array were obtained using all available scanner-transducer combinations while maintaining all scan parameters and the sample volume in the same tube location. Differences in PVs between center and edge apertures were compared across 4 constant flow rates. The averaged PVs for all phantom flow rates ranged from 24.4 cm/s to 138.2 cm/s from the array center. The averaged PVs from the center aperture were significantly greater than the corresponding measurements from the edge aperture for each flow rate (all p < 0.001). The relative PV differences ranged from 6.7% to 19.4% across all transducers and flow rates. Significantly lower PVs were consistently shown with the Doppler beam aperture at the array edge compared to center among all tested systems. This may be due to a narrower aperture width, shifted central axis, and less intrinsic spectral broadening error at the array edge. Controlling variations in Doppler aperture location is important in clinical applications which depend on consistent velocity measurements. [ABSTRACT FROM AUTHOR]

To understand the fluid hydraulic behavior change in a fracture under different shear displacements, fluid flow simulations at different flow velocities are carried out based on the Navier–Stokes equation. We characterized and conducted statistics on the change and distribution of the fracture aperture under different shear displacements, especially the measurement of the contact area under shear displacement, which was helpful for accurately studying the effect of shear displacement on fracture fluid flow. The results showed that the shear displacement of a fracture could be regarded as dislocation between the upper and lower fracture surfaces. The fluid flow velocity became larger near the contact sites and the streamlines became denser. The resulting hydraulic aperture exhibited a negative correlation with the contact area. The relationship between the volumetric flow rate and pressure gradient during the flow field simulation could be well-fitted by the Forchheimer equation, and the steepness of the curves was related to the contact area. The linear coefficient a and the nonlinear coefficient b in the Forchheimer equation were positively correlated with the contact area. Based on the measured flow velocity, the mechanical aperture was usually an order of magnitude larger than the hydraulic aperture. The linear relationship between the mechanical aperture and hydraulic aperture was described. The positive correlation between the permeability and mechanical aperture profiled during shear explained the hydraulic behavior in the flow field. [ABSTRACT FROM AUTHOR]

Electron beam (e‐beam) with a small spot size is the key to produce microfocus x‐ray source. The spot size of the e‐beam can be controlled by changing the aperture angle at the target, and the focus size of the microfocus x‐ray source is changed accordingly. At the same time, the SNR (Signal‐to‐Noise Ratio) of the image is reduced because the aperture produces secondary x‐ray, which interferes with the x‐ray imaging. In this paper, the aperture size and its position are optimized for getting the smallest spot size of the e‐beam, and the experimental results show that the resolution is 0.8 μm with the aperture size of 0.5 mm. In addition, this paper also presents that the image's SNR can be improved by coating carbon film on the back surface of the aperture. [ABSTRACT FROM AUTHOR]

Purpose: Proton stereotactic radiosurgery (PSRS) has emerged as an innovative proton therapy modality aimed at achieving precise dose delivery with minimal impact on healthy tissues. This study explores the dosimetric outcomes of PSRS in comparison to traditional intensity‐modulated proton therapy (IMPT) by focusing on cases with small target volumes. A custom‐made aperture system designed for proton therapy, specifically tailored to small target volumes, was developed and implemented for this investigation. Methods: A prerequisite mechanical validation through an isocentricity test precedes dosimetric assessments, ensuring the seamless integration of mechanical and dosimetry analyses. Five patients were enrolled in the study, including two with choroid melanoma and three with arteriovenous malformations (AVM). Two treatment plans were meticulously executed for each patient, one utilizing a collimated aperture and the other without. Both plans were subjected to robust optimization, maintaining identical beam arrangements and consistent optimization parameters to account for setup errors of 2 mm and range uncertainties of 3.5%. Plan evaluation metrics encompassing the Heterogeneity Index (HI), Paddick Conformity Index (CIPaddick), Gradient Index (GI), and the R50% index to evaluate alterations in low‐dose volume distribution. Results: The comparative analysis between PSRS and traditional PBS treatment revealed no significant differences in plan outcomes, with both modalities demonstrating comparable target coverage. However, collimated apertures resulted in discernible improvements in dose conformity, dose fall‐off, and reduced low‐dose volume. Conclusions: This study underscores the advantageous impact of the aperture system on proton therapy, particularly in cases involving small target volumes. [ABSTRACT FROM AUTHOR]

The main objective of this research was to conduct a comparative pollen morphological analysis of some representatives of the genus Cuscuta in relation to taxonomy. Investigations of 38 species and 1 variation revealed that not only the number, but the colpi length, as well as the exine ornamentation (at the SEM level), can be regarded as a diagnostic feature. For all the taxa studied, the common zonocolpate type of pollen was observed, represented by three variations: I) colpi long; II) colpi of medium length; III) colpi short. In combination with colpi length, variations in the number of colpi were also identified, such as: I) 3(4)-zonocolpate pollen grains with long colpi (in most of the species studied from subgenera Grammica and Cuscuta , as well as in C. monogyna from the subgenus Monogynella ); II) 4(3)-zonocolpate pollen grains, with long colpi ( C. cristata from subgenus Grammica ); III) 3-zonocolpate pollen grains both with long colpi and colpi of medium length ( C. abyssinic a from subgenus Cuscuta and C. africana , C. angulata from subgenus Pachystigma ); IV) 3-zonocolpate pollen grains with colpi of medium length were noted for species from all four subgenera ( C. cassytoides , C. lupuliformis from subgenus Monogynella , C. kotschyana from subgenus Cuscuta , C. nitida from subgenus Pachystigma and C. jalapensis , C. rostrata , C. suaveolens from subgenus Grammica ); V) 3–4- or 4-zonocolpate, with short colpi ( C. lehmanniana and C. gigantea from subgenus Monogynella respectively); VI) 5–6-zonocolpate, with short colpi ( C. reflexa from subgenus Monogynella ). Using SEM, three main types of exine ornamentation were also identified: perforate, foveolate and reticulate. The last type in the vast majority of the cases was presented in combination with echinae (rarely with spines or granules). The data revealed that the presence of the significant similarity of palyno-morphological characteristics in representatives of the subgenera Cuscuta , Pachystigma and Grammica , with the exception of the species Lepidanche adpressa (syn. C. compacta ), makes it difficult to create an identification key at the level of individual subgenera. Pollen features can be most clearly used only to distinguish the subgenus Monoginella , reflecting its certain isolation within the entire Cuscuta genus. The presence of a highly specialized reticulate exine ornamentation in Lepidanche adpressa (syn. C. compacta ), not identified for the pollen of any of the studied taxa of the subgenus Grammica , indicates a significant proximity of this species to the subgenus Monogynella . For the species C. reflexa , the obtained palyno-morphological data are consistent with the previous opinion about the separation of this species, as well as its more advanced position within the genus Cuscuta .

The review article summarizes the most significant results of research on the creation of antenna systems for mobile radio communications and radar, carried out at the Department of Information Radio Technologies of the Belarusian State University of Informatics and Radioelectronics over the last decade. New algorithms for the functioning of antenna matching devices for mobile radio communications in the VHF wavelength range, features of the construction of sub-aperture antenna arrays for radar equipment with broadband probing signals, and algorithms for processing signals in detectors-measurers of the angular coordinates of air objects with a multi-channel antenna system are considered. Promising areas of research on this topic are proposed.

Accurate measurement of the evolution of rock joint void geometry is essential for comprehending the distribution characteristics of asperities responsible for shear and seepage behaviors. However, existing techniques often require specialized equipment and skilled operators, posing practical challenges. In this study, a cost-effective photogrammetric approach is proposed. Particularly, local coordinate systems are established to facilitate the alignment and precise quantification of the relative position between two halves of a rock joint. Push/pull tests are conducted on rock joints with varying roughness levels to induce different contact states. A high-precision laser scanner serves as a benchmark for evaluating the photogrammetry method. Despite certain deviations exist, the measured evolution of void geometry is generally consistent with the qualitative findings of previous studies. The photogrammetric measurements yield comparable accuracy to laser scanning, with maximum errors of 13.2% for aperture and 14.4% for void volume. Most joint matching coefficient (JMC) measurement errors are below 20%. Larger measurement errors occur primarily in highly mismatched rock joints with JMC values below 0.2, but even in cases where measurement errors exceed 80%, the maximum JMC error is only 0.0434. Thus, the proposed photogrammetric approach holds promise for widespread application in void geometry measurements in rock joints.

This study compares the capital and operating costs of RGB OLED notebook panels patterned by conventional FMM to an alternative photolithographic approach. The results are used to analyze the benefits and challenges of each technology and how those may influence the rapidly growing OLED IT panel market. [ABSTRACT FROM AUTHOR]

Key Message: Innovatively, we consider stomatal detection as rotated object detection and provide an end-to-end, batch, rotated, real-time stomatal density and aperture size intelligent detection and identification system, RotatedeStomataNet. Stomata acts as a pathway for air and water vapor in the course of respiration, transpiration, and other gas metabolism, so the stomata phenotype is important for plant growth and development. Intelligent detection of high-throughput stoma is a key issue. Nevertheless, currently available methods usually suffer from detection errors or cumbersome operations when facing densely and unevenly arranged stomata. The proposed RotatedStomataNet innovatively regards stomata detection as rotated object detection, enabling an end-to-end, real-time, and intelligent phenotype analysis of stomata and apertures. The system is constructed based on the Arabidopsis and maize stomatal data sets acquired destructively, and the maize stomatal data set acquired in a non-destructive way, enabling the one-stop automatic collection of phenotypic, such as the location, density, length, and width of stomata and apertures without step-by-step operations. The accuracy of this system to acquire stomata and apertures has been well demonstrated in monocotyledon and dicotyledon, such as Arabidopsis, soybean, wheat, and maize. The experimental results that the prediction results of the method are consistent with those of manual labeling. The test sets, the system code, and their usage are also given (). [ABSTRACT FROM AUTHOR]

This study introduces a method of using a composite absorber, including a magnetic absorber, to maintain or improve shielding effectiveness, even if the metallic enclosure has unintentional and intentional apertures. The proposed structure places absorbers on the inner side of an enclosure’s aperture. The electric fields entering the enclosure through the aperture primarily decrease as they pass through the absorber, degrading the resonance characteristics of the enclosure by an inner absorber, thereby reducing the electric field strength within an enclosure and consequently improving the shielding property. A 3D numerical analysis confirmed the improved shielding property of the enclosure [ABSTRACT FROM AUTHOR]

Genus Cornus L. (Cornaceae) includes, according to various sources, from 4 to about 60 species, growing mainly in temperate regions of the northern hemisphere. Cornus mas L. is the most widely used species in the genus, from which numerous semi-cultivated and cultivated forms and sorts were obtained. The wild C. mas is of Western Asian origin, distributed in the mountains of the Caucasus, Asia Minor, and Southern Europe, and the genotype of the species shows reliable polymorphism. The purpose of this study was to present a detailed palynomorphological characteristic of the species C. mas of the Armenian flora using light microscopy (LM) and scanning electron microscopy (SEM), to clarify the disagreements noted in the literature regarding to the pollen aperture type for the species C. mas, as well as to conduct a comparative palynomorphological analysis of the genus Cornus as a whole (based on the literary data). The data obtained are consistent with the opinion of a number of authors about the presence in the species C. mas of the quite rare compound pollen aperture type. This compound aperture type is formed by a combination of the colpus with a peculiar endoaperture complex, consisting of a small oblong os and paracolpi, located on both sides of the colpi. The os small, elliptical, reaching the paracolpi, forming together butterfly-like or H-shape endexine thinnings. In our opinion, both the os and the paracolpi arose due to the thinning or absence of the internal layers of the exine. Exine 1.3–1.5 μm, columellae separate, thick, capitate. Exine ornamentation verrucate (LM); exine ornamentation densely verrucate with rare perforations, verrucae varying in size (SEM). An extensive analysis of the literature data on pollen of 42 species of the genus Cornus revealed the significant differences in the characteristics of the type of apertures not only at the interspecific, but also at the intraspecific level. In terms of size, pollen grains are predominantly large or of medium size, rarely small. The large pollen grains were noted for C. alba L., C. alsophila W. W. Sm., C. alternifolia L.f., C. amomum Mill., C. asperifolia Michx., C. controversa Hemsl., C. coreana Wangerin, C. drummondii C. A. Mey., C. excelsa Kunth, C. glabrata Benth., C. hemsleyi C. K. Schneid. & Wangerin, C. monbeigii Hemsl., C. paucinervis Hance, C. poliophylla C. K. Schneid. & Wangerin, C. rugosa Lam., C. sanguinea L., C. sericea L., C. stolonifera Michx., C. walteri Wangerin, C. wilsoniana Wangerin. Medium pollen size is typical for C. boliviana J. F. Macbr., C. brachypoda C. A. Mey., C. canadensis L., C. capitata Wall., C. chinensis Wangerin, C. controversa, C. disciflora Moc. & Sessé ex DC., C. floccosa Wangerin, C. florida Hook., C. foemina Mill., C. hongkongensis Hemsl., C. kousa Buerger, C. longipetiolata Hay., C. macrophylla Wall., C. mas L., C. nuttallii Audubon, C. oblonga Wall., C. peruviana J. F. Macbr., C. sericea, C. sessilis Torr., C. suecica L., C. ulotricha C. K. Schneid. & Wangerin, C. unalaschkensis Ledeb. The largest pollen grains were noted for the species C. monbergii (P x E = 81.0 x 48.5 μm) and the smallest ones for C. officinalis (P x E = 20.0 x 21.0 μm). Exine ornamentation as a rule is represented by a number of primitive types, namely, scabrate, rugulate, verrucate, granulate, echinate, etc., sometimes with perforations.

To analyze the effects of a time-varying viscosity on the penetration length of grouting, in this study cement slurries with varying water-cement ratios have been investigated using the Bingham's fluid flow equation and a discrete element method. A fluid-solid coupling numerical model has been introduced accordingly, and its accuracy has been validated through comparison of theoretical and numerical solutions. For different fracture forms (a single fracture, a branch fracture, and a fracture network), the influence of the time-varying viscosity on the slurry length range has been investigated, considering the change in the fracture aperture. The results show that under different fracture forms and the same grouting process conditions, the influence of the time-varying viscosity on the seepage length is 0.350 m. [ABSTRACT FROM AUTHOR]

The perforated paper honeycomb structure with double-hole in cell walls is one kind of innovative sandwich structure also to improve drying process of traditional honeycomb paperboard. Based on the analytical calculation, experiment inspection and finite element analysis, this paper is focus on the paper honeycomb core layer with double-hole in cell walls, and especially studies the bending and folding deformation and the compressive strength under out-of-plane quasi-static compression for different humidity. The structure first appears elastic buckling and folds near the circular holes in the cell wall, and goes on buckling, folding and crushing until to the densification with the continuously increase of compression set. Its quasi-static compressive stress and strain curve mainly shows four kinds of compression deformation processes, such as linear elastic stage, elastic yielding stage, plastic collapse stage, and densification stage. The critical stress and plateau stress of the structure slowly decrease with the increase of humidity and aperture, and the multiple linear regression analysis result illustrates that the relative humidity has much more influence on the critical stress and plateau stress. For different humidity and aperture, the analytical calculation result is close to the experiment result. However, the finite element simulation result greatly deviates from the above two results, especially for relative humidity 50% and 60% cases. [ABSTRACT FROM AUTHOR]

The main objective of this research was to conduct a comparative pollen morphological analysis of some representatives of the genus Cuscuta in relation to taxonomy. Investigations of 38 species and 1 variation revealed that not only the number, but the colpi length, as well as the exine ornamentation (at the SEM level), can be regarded as a diagnostic feature. For all the taxa studied, the common zonocolpate type of pollen was observed, represented by three variations: I) colpi long; II) colpi of medium length; III) colpi short. In combination with colpi length, variations in the number of colpi were also identified, such as: I) 3(4)-zonocolpate pollen grains with long colpi (in most of the species studied from subgenera Grammica and Cuscuta, as well as in C. monogyna from the subgenus Monogynella); II) 4(3)-zonocolpate pollen grains, with long colpi (C. cristata from subgenus Grammica); III) 3-zonocolpate pollen grains both with long colpi and colpi of medium length (C. abyssinica from subgenus Cuscuta and C. africana, C. angulata from subgenus Pachystigma); IV) 3-zonocolpate pollen grains with colpi of medium length were noted for species from all four subgenera (C. cassytoides, C. lupuliformis from subgenus Monogynella, C. kotschyana from subgenus Cuscuta, C. nitida from subgenus Pachystigma and C. jalapensis, C. rostrata, C. suaveolens from subgenus Grammica); V) 3–4- or 4-zonocolpate, with short colpi (C. lehmanniana and C. gigantea from subgenus Monogynella respectively); VI) 5–6-zonocolpate, with short colpi (C. reflexa from subgenus Monogynella). Using SEM, three main types of exine ornamentation were also identified: perforate, foveolate and reticulate. The last type in the vast majority of the cases was presented in combination with echinae (rarely with spines or granules). The data revealed that the presence of the significant similarity of palyno-morphological characteristics in representatives of the subgenera Cuscuta, Pachystigma and Grammica, with the exception of the species Lepidanche adpressa (syn. C. compacta), makes it difficult to create an identification key at the level of individual subgenera. Pollen features can be most clearly used only to distinguish the subgenus Monoginella, reflecting its certain isolation within the entire Cuscuta genus. The presence of a highly specialized reticulate exine ornamentation in Lepidanche adpressa (syn. C. compacta), not identified for the pollen of any of the studied taxa of the subgenus Grammica, indicates a significant proximity of this species to the subgenus Monogynella. For the species C. reflexa, the obtained palyno-morphological data are consistent with the previous opinion about the separation of this species, as well as its more advanced position within the genus Cuscuta. [ABSTRACT FROM AUTHOR]

Stomata are the key nodes linking photosynthesis and transpiration. By regulating the opening degree of stomata, plants successively achieve the balance between water loss and carbon dioxide acquisition. The dynamic behaviour of stomata is an important cornerstone of plant adaptability. Though there have been miscellaneous experimental results on stomata and their constituent cells, the guard cells and the subsidiary cells, current theory of stomata regulation is far from clear and unified. In this work, we develop an integrated model to describe the stomatal dynamics of seed plants based on existing experimental results. The model includes three parts: (1) a passive mechanical model of the stomatal aperture as a bivariate function of the guard‐cell turgor and the subsidiary‐cell turgor; (2) an active regulation model with a target ion‐content in guard cells as a function of their water potential; and (3) a dynamical model for the movement of potassium ions and water content. Our model has been used to reproduce abundant experimental phenomena semi‐quantitatively. With accurately measured parameters, our model can also be used to predict stomatal responses to changes of environmental conditions. Summary statement: A stomata model is developed based on existing experiments and reproduces important stomatal behaviour. The model takes into account passive mechanical interaction between guard cells and subsidiary cells, active movement of potassium ions, and water transport driven by water potential. [ABSTRACT FROM AUTHOR]

During the long service period of a nuclear waste repository in crystalline rock, large earthquake(s) may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures within the geological formation. The resulting fracture normal/shear displacements may lead to fracture opening and further promote the transport of leaked radionuclides into the groundwater system. Thus, it is of central importance to analyze the consequences of potential future earthquake(s) on the hydrogeological properties of a repository site for spent nuclear fuel disposal. Based on the detailed site characterization data of the repository site at Forsmark, Sweden, we conduct a three-dimensional (3D) seismo-hydro-mechanical simulation using the 3Dimensional Distinct Element Code (3DEC). We explicitly represent a primary seismogenic fault zone and its surrounding secondary fracture network associated with a power-law size scaling and a Fisher orientation distribution. An earthquake with a magnitude of Mw = 5.6 caused by the reactivation of the primary fault zone is modeled by simulating its transient rupture propagating radially outwards from a predefined hypocenter at a specified rupture speed, with the faulting dynamics controlled by a strength weakening law. We model the coseismic response of the off-fault fracture network subject to both static and dynamic triggering effects. We further diagnose the distribution of fracture hydro-mechanical properties (e.g. mechanical/hydraulic aperture, hydraulic transmissivity) before and after the earthquake in order to quantify earthquake-induced hydraulic changes in the fracture network. It is found that earthquake-induced fracture transmissivity changes tend to follow a power-law decay with the distance to the earthquake fault. Our simulation results and insights obtained have important implications for the long-term performance assessment of nuclear waste repositories in fractured crystalline rocks.

This article applies the proposals for the internal structure of vowels made within Government Phonology (GP) 2.0 (Pöchtrager 2006, 2018) to vowel reduction in European Portuguese. GP 2.0 assumes that openness is a structural property and that reduction consists in removing parts of that structure. This approach not only allows us to model various reduction patterns, but also makes it possible to establish a non-arbitrary link between differences in the extent of reduction and the context where it occurs. As will be shown throughout the text, taking aperture as structural has broader cross-linguistic coverage than existing alternatives.

Macroscopic nonlinear flow, which is closely related to mesoscopic flow structures such as vortices, is an important property of fluid flow and solute transport in rock fractures with a high pressure gradient. Both mesoscopic flow structure and macroscopic nonlinear flow of rock fractures are affected by fracture roughness and aperture. Therefore, the macroscopic seepage process in fractures is studied numerically by directly solving the Navier–Stokes equation. The results demonstrate that the Forchheimer equation can be used to describe the relationship between flow rate and pressure gradient of rough fractures with different apertures. The linear and nonlinear coefficients of the Forchheimer equation increase with fracture roughness and decrease with fracture aperture. Empirical formulas between the linear coefficient, the nonlinear coefficient, the fracture roughness and aperture are established. When the roughness is equal to zero, the empirical formulas can degenerate into conventional cubic law. In additions, the distribution characteristics of the mesoscopic flow structure in rough fractures are also investigated. The results show that the area and kinetic energy distribution characteristics of the mesoscopic flow structure in fractures with different roughness and apertures are similar. The frequency characteristics of the area and kinetic energy of the mesoscopic flow structure in fractures can be fitted with negative exponential and logarithmic normal functions, respectively. The effect of fracture roughness on area and kinetic energy distribution characteristics is significant, but the effect of aperture can be ignored. Empirical formulas between fracture roughness and mesoscopic flow structure characteristics are established for the first time. [ABSTRACT FROM AUTHOR]

Earrings and other things that a woman adorns with are part of the complement of her adornment and elegance. Piercing the ear and nose is one of the purposes by which one achieves desirable adornment for females. God Almighty said, “Is he who grows up in adornment while he is not clear in a quarrel?” [Surat Al-Zukhruf: Verse 18], This has been their custom in ancient and modern times, whether the earrings or the like are small or large, although this action is not without suffering, pain, or sensitivity sometimes. This is why we find that there are jurists who do not allow this matter. Because of the harm and pain it entails, while we find that another group of them permitted this matter on the grounds that the pain that accompanies it is minor, and because it is in the interest of women in terms of beautification and adornment; For this reason, we decided to study the ruling on piercing the ears of a female and a boy, and piercing their nose (a comparative study); To explain the sayings of jurists and present their evidence on these issues. This study required that the research consist of an introduction and three claims. As for the introduction: it stated the reasons for choosing the topic, its importance, its objectives and difficulties, previous studies, and then the research plan. The first requirement: What is the ruling on piercing a female’s ear? The second requirement: regarding the ruling on piercing a female’s nose. The third requirement: What is the ruling on piercing a boy’s ear? This is followed by a conclusion in which I mentioned the most important findings that I reached through my study of these issues, and finally a list of sources and references. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics simulations are used to obtain a radially symmetrical flow profile at an aperture of a microfluidic channel by manually arranging flow‐directing obstacles around the aperture. For the first time, the flow profile is improved by calculating the coefficient of variation (CoV), which is applied to the flow velocity magnitude along coaxially arranged circles below the aperture in the microfluidic channel. A minimum CoV of 0.03 is obtained at the circle with the same diameter as the aperture. Channels with the optimized design are fabricated by lamination of two layers of dry film resist and patterned with UV‐lithography. The aperture is formed by using an inductively coupled plasma reactive ion etching process. Video recording of the flow behavior confirmed the simulation results experimentally. The proposed channel design and the optimization method can favorably be used for a balanced hydrodynamic trapping of particles or cells at apertures. [ABSTRACT FROM AUTHOR]

Glacial till bluffs along Lake Erie’s shoreline, northeastern Ohio, contain three sets of joints that influence the hydraulic behavior of till mass like joints in rock influence the hydraulic behavior of rock mass. According to the Unified Soil Classification System, the till classifies as low plasticity silt to low plasticity clay, with a clay content of 36–41 percent. Mineralogically, it consists of quartz, illite, and kaolinite. The joints in till are either open or filled with sand, silt, or both from the overlying lacustrine material or with disintegrated till from the joint walls. We used double-ring infiltration and dye tests to estimate field permeability. Laboratory permeability tests were performed on dry and saturated samples of till material, with manually created joints that were either kept open or filled with sand or disintegrated till material to simulate field conditions. Field and laboratory test results showed that permeability of jointed till depended upon whether the joints were open or filled, the nature of the joint-filling material, and the water content of the till (dry versus saturated) and that permeability generally decreased with increasing test time. Dry samples exhibited a substantially larger decrease in permeability than saturated samples, with the largest decrease occurring during the first 24 hours. Open joints in dry samples collapsed during the test procedure, and the permeability of these samples was generally similar to the permeability of the collapsed till material. Permeability tests on saturated samples with open joints were inconclusive. We present a comparison of field and laboratory test results. [ABSTRACT FROM AUTHOR]

The article analyzes the role of lighting in portrait photography, emphasizing how the harmony between light and shadow can affect the emotional depth and visual appeal of an image. Photography, presented as an art and science of light, requires not only professional skills, but also the talent and skill of the photographer. The skill of a photographer lies not only in technical execution, but also in the ability to convey life and emotions through the image, revealing the true character of a person. Thus, a portrait photographer should be able to capture the soul and inner world of the model, which is a sign of his or her true skill. The article pays special attention to lighting under artificial lighting. It further discusses such aspects as distance between the subject and the light source, directionality of light, the size of light source and the distance to the subject, as well as the importance of shape of reflector. The different types of lighting in portrait photography are also discussed: back, side, front, diffused, and hard light, each of which affects the final image. The study includes analysis of current trends and innovative lighting techniques in portrait photography. It emphasizes the importance of the photographer's ability to use different light sources to create images that reflect uniqueness and personality of the model. This study aims to expand the theoretical knowledge and practical skills of photographers, striving to improve the quality and expressiveness of portrait images. [ABSTRACT FROM AUTHOR]

The micromorphology and functional properties of aerogels from rice, pea, potato or corn starch were characterized by a scanning electron microscope (SEM), an automatic surface area and pore size analyzer, an X-ray diffractometer, and a texture analyzer. The findings revealed that all the four starch aerogels had low density and high porosity. Under SEM observation, rice starch aerogel showed a lamellar structure, pea and potato starch aerogels showed a porous structure with uneven pore size distribution and thick pore walls in some zones, and corn starch aerogel presented a good three-dimensional network structure. The average pore sizes of the four starch aerogels were not much different, mainly distributed in the range of 5–13 nm, whereas there were differences in specific surface area, being smallest in pea starch aerogel (0.330 m2/g) and largest in corn starch aerogel (0.562 m2/g). The X-ray diffraction results showed that the crystallinity of these four starches declined after gelatinization and retrogradation, with corn starch experiencing the greatest decrease, from 30.71% to 8.13%. Compared with pea and potato starch aerogels, corn starch aerogel had higher solubility, water absorption rate, and Young’s modulus (6.233 MPa), and showed stronger deformation resistance, indicating excellent aerogel performance.

Pollen morphology and ultrastructure was studied for the monotypic genus Lysiostyles (Convolvulaceae, tribe Maripeae) distributed in Guyana, Suriname and Venezuela. Lysiostyles scandens is a liana with alternate leaves, thyrsiform inflorescence, white corolla with acuminate lobes, five epipetalous stamens, anthers with elongated connectives and a superior ovary with two carpels. The styles are glabrous, branched and divided at the base with cylindrical stigma and lignified and indehiscent fruits. Pollen was collected from specimens in the herbaria RB, L, and U. For observation under light microscopy (LM) and scanning electron microscopy (SEM), pollen grains were prepared using acetolysis. Non-acetolysed pollen grains were prepared for observation by transmission electron microscopy (TEM). Pollen is small to medium sized, isopolar, mostly subprolate, and subcircular amb, tricolpate and tectate with a wavy relief and microechinate tectum. The sexine is thicker than the nexine. The pollen features observed in Lysiostyles are important for the characterisation of the genus, as well as for understanding relationships within the tribe Maripeae (Dicranostyles and Maripa), and support patterns suggested by phylogenetic studies. [ABSTRACT FROM AUTHOR]

It is of great significance to study the fracture closure process and contact area under normal stress to quantitatively study the stress and strain of engineering rock surfaces. A mechanical analysis model of the relationship between the mesoscopic mechanical aperture and the normal deformation of fractured media under elastic conditions is established based on the finite element method. The change in the contact area of the fracture surfaces under normal stress at different levels is studied. The distribution of the contact stress, the distribution of the fracture closure, and the change in the asperity at each contact point are described in detail. The results show that the normal stress and normal deformation of the fracture exhibit a nonlinear relationship, and the normal stiffness decreases with increasing stress. The local deformation of fractures also follows this rule. Under different levels of stress, the aperture always maintains a Gaussian distribution, and as the normal stress increases, the increased contact area reduces the standard deviation of the aperture distribution. The theoretically calculated results are validated, demonstrating the accuracy and predictability of the model. Highlights: A contact model was proposed to show fracture mesoscopic deformation characteristics. The lateral distribution of the contact stress was proposed for the first time. The accuracy of the macroscopic mechanical analysis was improved. [ABSTRACT FROM AUTHOR]

The nonlinear flow properties of Newtonian fluids through crossed fractures are estimated by considering the influences of length, aperture, and surface roughness of fractures. A total of 252 computational runs are performed by creating 36 computational domains, in which the Navier-Stokes equations are solved. The results show that the nonlinear relationship between flow rate and hydraulic gradient follows Forchheimer's law--based equation. When the hydraulic gradient is small (i.e., 10-6), the streamlines are parallel to the fracture walls, indicating a linear streamline distribution. When the hydraulic gradient is large (i.e., 10°), the streamlines are disturbed by a certain number of eddies, indicating a nonlinear streamline distribution. The patterns of eddy distributions depend on the length, aperture, and surface roughness of fractures. With the increment of hydraulic gradient from10-6 to 10°, the ratio of flow rate to hydraulic gradient holds constants and then decreases slightly and finally decreases robustly. The fluid flow experiences a linear flow regime, a weakly nonlinear regime, and a strongly nonlinear regime, respectively. The critical hydraulic gradient ranges from 3.27x10-5 to 5.82x10-2 when fracture length=20-100 mm and mechanical aperture=1-5mm. The joint roughness coefficient plays a negligible role in the variations in critical hydraulic gradient compared with fracture length and/or mechanical aperture. The critical hydraulic gradient decreases with increasing mechanical aperture, following power-law relationships. The parameters in the functions are associated with fracture length. [ABSTRACT FROM AUTHOR]

Background and purpose: Proton therapy is a key modality used in the treatment of ocular melanoma. Traditionally ocular sites are treated using a dedicated eyeline with a passively scattered proton beam and a brass aperture. This work aims to design and characterize a beam‐collimating aperture to treat ocular targets with a gantry‐based spot scanning proton beam. Methods: A plastic aperture system that slides into the gantry nozzle of a spot scanning proton beam was designed and constructed. It consists of an intermediate scraper layer to attenuate stray protons and a 3D‐printed patient‐specific aperture positioned 5.7 cm from the surface of the eye. The aperture system was modeled in TOPAS and Monte Carlo simulations were validated with film measurements. Two different spot configurations were investigated for treatment planning and characterized based on lateral penumbra, central axis (CAX) dose and relative efficiency. Alignment and leakage were investigated through experimental film measurements. Range was verified using a multi‐layer ionization chamber. Reference dose measurements were made with a PinPoint 3D ion chamber. Neutron dose was evaluated through Monte Carlo simulations. Results: Aperture alignment with radiation isocenter was determined to be within 0.31 mm at a gantry angle of 0°. A single‐spot configuration with a 10 mm diameter aperture yielded film‐measured lateral penumbras of 1 mm to 1.25 mm, depending on depth in the spread‐out Bragg peak. TOPAS simulations found that a single spot configuration results in a flat dose distribution for a 10 mm diameter aperture and provides a CAX dose of less than 106% for apertures less than 14 mm in diameter. For larger targets, adding four corner spots to fill in the dose distribution is beneficial. Trade‐offs between lateral penumbra, CAX dose and relative efficiency were characterized for different spot configurations and can be used for future clinical decision‐making. The aperture was experimentally determined to not affect proton beam range, and no concerning leakage radiation or neutron dose was identified. Reference dose measurements with a PinPoint ion chamber were within 2.1% of Monte Carlo calculated doses. Conclusion: The aperture system developed in this work provides a method of treating ocular sites on a gantry‐based spot scanning proton system. Additional work to develop compatible gaze tracking and gating infrastructure is ongoing. [ABSTRACT FROM AUTHOR]

The study of microfractures in shale is mainly based on qualitative description. Conversely, quantitative description of the parameters of shale microfractures can provide a quantitative basis for shale fracture characterization and shale physical properties. Nine shale reservoir samples of the Wufeng–Longmaxi Formation in the Jiaoshiba area were studied, using the backscattered two-dimensional multiscale resolution imaging technology, combined with high-resolution map imaging technology (MAPS), and thousands of images were obtained using scanning electron microscopy. Gray image analysis was used to extract microfracture information from images (2 × 2 cm multiresolution). The "maximum circle method" was used to calculate the length and aperture characteristics of the fractures. Parameters such as the area of the bedding fractures, the surface rate of the fractures, and the linear density of the fractures were obtained by the integration of apertures. The fracture length was between 2~7 mm, the aperture was between 1~6 μm, the linear density was between 1~6/m and the surface rate was 1%. The bedding fractures do not contribute much to the porosity of the shale reservoir; however, shale reservoirs with high porosity have a high development of bedding fractures and good permeability. The development of a bedding fracture is controlled by the lithology within shale reservoirs. Different types of lithology contain different bedding fractures, but they have a certain regularity. Moreover, the content of organic matter and TOC (total organic content) in the shale reservoir control the development of a bedding fracture, where a high organic and TOC content are accompanied by a high number of fractures. [ABSTRACT FROM AUTHOR]

We present results from an international model comparison study involving a series of controlled fault activation experiments in Opalinus Clay at the Mont Terri Laboratory, Switzerland. The fault activation experiments were conducted in situ by water injection at variable pressure from boreholes targeting different parts of the Main Fault crossing several tunnels and galleries of the Mont Terri Laboratory. The model simulations focused on (1) an experiment activating a discontinuity (fracture or minor fault) within the damage zone of the main fault, and (2) an experiment activating discontinuities close to the core of the Main Fault. The experimental data consist of coupled hydraulic and mechanical responses monitored at an injection borehole and a monitoring borehole located a few meters away. After overcoming several modeling issues along with necessary model developments, a reasonably good agreement was achieved between the modeling results and the field observations. The fault activation experiments displayed an abrupt flow rate increase associated with a sudden fracture opening and rupture propagation after the injection pressure reached above the estimated normal stress on the fracture. This was followed by an abrupt flow rate decrease, indicating hydraulic closing, once the injection pressure decreases to an estimated 1–2 MPa below the stress normal to the opened fracture. The models were able to capture this abrupt hydromechanical behavior, including an observed dominant opening behavior along with the rupture propagation, while the spatial extent of the shear rupture and the quantity of peak injection flow were the most challenging to predict.

We present results from an international model comparison study involving a series of controlled fault activation experiments in Opalinus Clay at the Mont Terri Laboratory, Switzerland. The fault activation experiments were conducted in situ by water injection at variable pressure from boreholes targeting different parts of the Main Fault crossing several tunnels and galleries of the Mont Terri Laboratory. The model simulations focused on (1) an experiment activating a discontinuity (fracture or minor fault) within the damage zone of the main fault, and (2) an experiment activating discontinuities close to the core of the Main Fault. The experimental data consist of coupled hydraulic and mechanical responses monitored at an injection borehole and a monitoring borehole located a few meters away. After overcoming several modeling issues along with necessary model developments, a reasonably good agreement was achieved between the modeling results and the field observations. The fault activation experiments displayed an abrupt flow rate increase associated with a sudden fracture opening and rupture propagation after the injection pressure reached above the estimated normal stress on the fracture. This was followed by an abrupt flow rate decrease, indicating hydraulic closing, once the injection pressure decreases to an estimated 1–2 MPa below the stress normal to the opened fracture. The models were able to capture this abrupt hydromechanical behavior, including an observed dominant opening behavior along with the rupture propagation, while the spatial extent of the shear rupture and the quantity of peak injection flow were the most challenging to predict.

In this study, the combined effects of geometrical distribution and geomechanical deformation of fracture networks on fluid flow through fractured geological media are investigated numerically. We consider a finite-sized model domain in which the geometry of fracture systems follows a power-law length scaling. The geomechanical response of the fractured rock is simulated using a hybrid finite-discrete element model, which can capture the deformation of intact rocks, the interaction of matrix blocks, the displacement of discrete fractures and the propagation of new cracks. Under far-field stress loading, the locally variable stress distribution in the fractured rock leads to a stress-dependent variable aperture field controlled by compression-induced closure and shear-induced dilatancy of rough fractures. The equivalent permeability of the deformed fractured rock is calculated by solving for the fracture-matrix flow considering the cubic relationship between fracture aperture and flow rate at each local fracture segment. We report that the geometrical connectivity of fracture networks plays a critical role in the hydromechanical processes in fractured rocks. A well-connected fracture system under a high stress ratio condition exhibits intense frictional sliding and large fracture dilation/opening, leading to greater rock mass permeability. However, a disconnected fracture network accommodates much less fracture shearing and opening, and has much lower bulk permeability. We further propose an analytical solution for the relationship between the equivalent permeability of fractured rocks and the connectivity metric (i.e. percolation parameter) of fracture networks, which yields an excellent match to the numerical results. We infer that fluid flow through a well-connected system is governed by traversing channels (forming an “in parallel” architecture) and thus equivalent permeability is sensitive to stress loading (due to stress-dependent fracture permeability), whilst fluid flow through a disconnected system is more ruled by matrix (linking isolated clusters “in series”) and has much less stress dependency.

The quantification of fluid flow in rough fractures is of high interest for reservoir engineering, especially for deep geothermal applications. Herein, rough self-affine fractures are stochastically generated with incremental shear displacement and geometrically described by two aperture definitions, the vertical aperture avert and the effective aperture aeff. In order to compare their effect on fracture flow, such as anisotropy and channelling, Local Cubic Law (LCL) model-based 2D fluid flow is simulated. The particularity of this approach is the combination of a stochastic generation of self-affine fractures with a statistical analysis (560 individual realizations) of the impact of the LCL’s aperture constraint on fracture flow. The results show that aperture definition affects the quantitative interpretation of flow anisotropy and channeling as well as the aperture distribution of the fractures with shearing. Higher values of mean aperture for a given fracture are found using avert, whereas the aperture standard deviation is larger with aeff. In addition, flow anisotropy is significantly sensitive to aperture definition for small shear displacements and shows a relative higher dispersion with aeff. Thus, LCL prediction models based on avert are expected to lead to higher dispersion of anisotropy results with a higher uncertainty (factor ~ 2). Realizations based on avert lead to an enhanced clustering of high flow rates for higher shearing displacements. This channeling development results in higher total flow rates for these simulations. These findings support the direct calibration of pre-existing LCL anisotropy simulations based on avert towards more representative results using aeff.

Introduction. Acoustic profiling is a conventional method for studying the geological structure of the seabed. To this end, a low-frequency acoustic profiler with an operating frequency range of 1…14 kHz can be used. However, under lower operating frequencies, the difficulty of achieving the required resolution arises. The problem of improving the angular resolution of a hydroacoustic device, particularly in the direction of the carrier movement, remains to be a priority task in the search and detection of objects on the seabed, as well as the study of the bottom soil structure. Angular resolution can be improved through several approaches, including an algorithm for synthesizing the antenna aperture based on the law of the phase change of the reflected signal. This approach is relevant in the design of highresolution hydroacoustic tools.Aim. To demonstrate the possibility of constructing a bottom soil profiling device, as well as the possibility of increasing its angular resolution based on an algorithm for synthesizing the antenna aperture of an acoustic profiler.Materials and methods. The study employed the groundwork data obtained for side-scan sonars with a synthetic aperture in terms of constructing an antenna device and the methods of radio-wave excitation developed for radar systems.Results. The possibility of synthesizing the antenna aperture for an acoustic profiler of the bottom soil was studied. An algorithm for synthesizing the antenna aperture was investigated along with phase distortions of the trajectory signal and their influence on the sonar image. The fundamental principles of processing the trajectory signal were considered.Conclusion. An approach to increasing the resolution of an acoustic profiler when performing search and survey tasks is proposed. The proposed design of the acoustic part of a profiling device can be used in the development of search and survey hydroacoustic devices with a high angular resolution.

The article analyzes a flat circular aperture and proposes to use a new analytical expression that describes the radiation pattern of an elementary radiator of an antenna aperture depending on time and integration angle. The formula presented in the paper can be applied to any flat section of the aperture without taking into account its shape. A new equation for the antiderivative function of the impulse response of a circular aperture is presented in the form of an elliptic integral of the second kind. It is shown that the theoretically calculated results are in good agreement with numerical simulations. In the analysis of the numerical model, the method of finite integration in the time domain (FIT) was used. Due to the requirement of a large computational resource, the numerical model was simplified.

Surface acoustic wave (SAW) devices are key components in 5G communication systems, and the design of SAW filters with high frequency, high performance and high reliability is a necessary and challenging task. In this work, SAW resonators with $LiNbO_{3}/SiO_{2}/Si$ multi-layer structure are designed based on the spectral element method (SEM). Normally, however, massive computing resources are needed for solving a whole resonator directly by using full-wave numerical methods. To avoid simulating the large-aperture full structure of any SAW resonator, an equivalent small-aperture 3D structure can be modelled in the direction of the aperture by changing the internal resistance of the driving source to obtain the results of the full-scale aperture model. The one-port SAW resonators are then connected in the form of ladder networks to form band-pass SAW filters. The numerical results show that the SEM is more computationally efficient than the finite element method under the same number of degrees of freedom, and the results of the 3D small-aperture model are consistent with the complete resonator.

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The article describes the combination of experimental measurements with mathematical–physics analyses in flow investigation in the chambers of the scintillator detector, which is a part of the environmental scanning electron microscope. The chambers are divided with apertures by small openings that keep the desirable pressure differences between three chambers: The specimen chamber, the differentially pumped intermediate chamber, and the scintillator chamber. There are conflicting demands on these apertures. On the one hand, the diameter of the apertures must be as big as possible so that they incur minimal losses of the passing secondary electrons. On the other hand, it is possible to magnify the apertures only to a certain extent so the rotary and turbomolecular vacuum pump can maintain the required operating pressures in separate chambers. The article describes the combination of experimental measurement using an absolute pressure sensor and mathematical physics analysis to map all the specifics of the emerging critical supersonic flow in apertures between the chambers. Based on the experiments and their tuned analyses, the most effective variant of combining the sizes of each aperture concerning different operating pressures in the detector is determined. The situation is made more difficult by the described fact that each aperture separates a different pressure gradient, so the gas flow through each aperture has its own characteristics with a different type of critical flow, and they influence each other, thereby influencing the final passage of secondary electrons detected by the scintillator and thus affecting the resulting displayed image. [ABSTRACT FROM AUTHOR]

Coussareeae is a neotropical tribe with a complex taxonomic history. Several authors considered it very close to the tribe Psychotrieae owing to similarities in their morphological characteristics, such as solitary ovules. The tribe Coussareeae constitutes the largest basal clade of the subfamily Rubioideae, and most of its genera are well represented in Brazil. The tribe is resolved into three suprageneric clades, including the Coccocypselum and Coussarea-Faramea clades, whose representatives are found in Brazil. This study aimed to ascertain whether pollen attributes corroborate the currently proposed phylogeny and systematics of the tribe. For this, pollen grains of 33 species belonging to the Coccocypselum and Coussarea-Faramea clades were analyzed. Specimens were obtained from herbaria, treated by the acetolysis method, measured, photographed, and described using light and scanning electron microscopy. Morphological analysis showed that pollen grains were medium (25–50 µm) or large (50–100 µm) in size; isopolar or apolar; 2-porate, 3-porate, or 3-colporate; and oblate spheroidal, suboblate, prolate spheroidal, or subprolate. Ornamentation varied among clade representatives. Multivariate analysis of quantitative data revealed that pollen diameter, apocolpium side, pore diameter, colpus length, and endoaperture width were the most significant characters. It can be seen from the results that the studied clades are formed by palynologically distinct genera in terms of polarity, aperture type, and ornamentation. Palynology confirms the proposed taxonomic classification. [ABSTRACT FROM AUTHOR]