Scanning Area Research Articles

The generation method of orthophoto expansion map of arched dome mural based on three-dimensional fine color model

Murals carry cultural significance and historical information, and are an important channel for understanding ancient social norms, artistic styles, and religious beliefs. At present, the digitization of murals is an important technical means for the protection of cultural heritage. Orthogonal images of murals play a vital role in high-precision recording, preservation, academic research, educational expansion, mural protection, digital exhibition and dissemination. At present, orthogonal images of murals are mostly realized by plane projection, but this method is not suitable for making orthogonal images of arched and dome-shaped murals. To address this problem, this paper proposes a method for generating orthogonal expansion images of arched and dome-shaped murals. This method combines a three-dimensional virtual space simulation model with an RTT virtual camera and adopts a spatial reference orthogonal ray scanning model. First, the detailed three-dimensional color model is fitted to the geometric reference of cylindrical and spherical objects to determine its parameters. Next, for the cylindrical murals on the arch, the orientation of the model is initialized using quaternions, and the viewport matrix is adjusted to obtain the required resolution. Then, the RTT camera is used to perform line orthogonal projection in the viewport, and the fringe projection image is generated by rotating around the cylinder axis according to the inversely calculated rotation angle. For the murals on the dome ceiling, this method is used to segment them according to a certain longitude, and the circumscribed cylinder of the fitted sphere is rotated to perform cylindrical orthogonal line scanning in the segmented area. These individual orthogonal line scan images are carefully spliced together to form a complete orthogonal unfolded image. Finally, a fringe projection image is generated with the central meridian of the unfolded part as the center line, and the fringe projection images are spliced together to obtain the final orthogonal unfolded image. Experiments show that compared with existing methods, this method can generate two-dimensional orthogonal unfolded images with high texture fidelity, minimal texture deformation, and uniform deformation distribution. This study provides a novel perspective on the orthogonal unfolding of quasi-cylindrical and quasi-spherical painted objects, and provides an accurate and diverse data basis for the digitization of murals.

Local Stiffness Measurement of Hepatic Steatosis Model Liver Organoid by Fluorescence Imaging-Assisted Probe Indentation.

Mechanical stiffness of liver organoid is a key indicator for the progress of hepatic steatosis. Probe indentation is a noninvasive methodology to measure Young's modulus (YM); however, the inhomogeneous nature of the liver organoid induces measurement uncertainty requiring a large number of indentations covering a wide scanning area. Here, we demonstrate that lipid-stained fluorescence imaging-assisted probe indentation significantly reduces the number of measurements by specifying the highly lipid-induced area. Lipid-stained hepatic steatosis model liver organoid shows broad fluorescence distributions that are spatially correlated with a decreased YM on a lipid-filled region with bright fluorescence compared with that measured on a blank region with dark fluorescence. The organoid viability remained robust even after exposure to an ambient condition up to 6 h, showing that probe indentations can be noninvasive methods for liver organoid stiffness measurements.

The Development of a 3D Magnetic Field Scanner Using Additive Technologies

Visualizing magnetic fields is essential for studying the operation of electromagnetic systems and devices that use permanent magnets or magnetic particles. However, commercial devices for this purpose are often expensive due to their complex designs, which may not always be necessary for specific research needs. This work presents a method for designing an automated laboratory setup for magnetic cartography, utilizing a 3D printer to produce structural plastic components for the scanner. The assembly process is thoroughly described, covering both the hardware and software aspects. Spatial resolution and mapping parameters, such as the number of data points and the collection time, were configured through software. Multiple tests were conducted on samples featuring flat inductive coils on a printed circuit board, providing a reliable model for comparing calculated and measured results. The scanner offers several advantages, including a straightforward design, readily available materials and components, a large scanning area (100 mm × 100 mm × 100 mm), a user-friendly interface, and adaptability for specific tasks. Additionally, the integration of a pre-built macro enables connection to any PC running Windows, while the open-source microcontroller code allows users to customize the scanner’s functionality to meet their specific requirements.

Development of a seat support mechanism for guiding users to an appropriate posture in a seated-style echocardiography robot

Abstract This paper proposes a seat support mechanism to solve the problem of misalignment between the chest examination and probe scanning areas when the patient is bent in a seated-style echocardiography robot. To guide the patient to an appropriate body position where their chest is within the examination range of the chest examination unit while minimizing the physical load of the patient, the posture of the patient must satisfy the three following conditions. (i) The breech must be in contact with the seat surface, (ii) the legs must be vertical to the floor, and (iii) the chest and mechanism must be parallel while the probe scanning and chest examination ranges must match. The human body was modeled to derive a posture that satisfies the aforementioned conditions for the height of each individual, and a seat support mechanism with four degrees of freedom was installed to guide the user to the derived posture. By installing this mechanism, the body load of the left biceps brachii, right biceps brachii, left latissimus dorsi, and right latissimus dorsi was reduced to 64.7%, 52.7%, 86.4%, and 80.2%, respectively. The sharpness of the image contours was improved to 103.8%.

Twisted Metasurfaces for On‐Demand Focusing Localization

AbstractDynamic focusing of electromagnetic (EM) waves is a cornerstone in various applications, encompassing aerospace communication, sensing, and high‐resolution imaging. Recently, the advent of intelligent metasurfaces, hailed as the next evolutionary step, has revolutionized self‐adaptive functionalities. However, their extensive embeddings of active components pose a great challenge associated with escalated costs, heightened power consumption, and increased complexity, thus hindering large‐scale implementation. Here, a cost‐effective approach for dynamic EM focusing utilizing a twisted metasurface is introduced, which integrates a transmissive layer with a reflective layer in a cascade fashion. This innovative design leverages the mutual rotation between two layers to enable the precise manipulation of beam propagation and scanning area, allowing for the flexible localization of the focal point across a wide range, spanning −44.17° to 44.17° in elevation and 0° to 360° in azimuth. This capability is underpinned by the strategic fusion of multiple phase profiles, including gradient and Gaussian phase. In the experiment, a goal‐oriented system is built up whose outcomes demonstrate a striking alignment with the simulated results, achieving a correlation coefficient of 96.7%. This work presents a streamlined pathway toward dynamic EM focusing and the related applications constrained by space and power limitations.

INtelligent toolkit for reconnaissance, assessments and prehospital support in Perilous InciDents: a realistic experiment in prehospital environment

BackgroundFirst responders, when arriving at a disaster, need a rapid analysis of the environment in which they are going to operate, as they have to assess the conditions surrounding potential victims and neutralize any risks that may exist.The EU-funded INTREPID develops a new technology platform to assist first responders when arriving on the scene of a disaster. The project INTREPID aims to support safer operations in the form of more efficient, fast, and safe disaster site assessments. The objective of the study is to implement new technologies into rescue operations to facilitate and improve situational awareness and operation management capabilities to save lives.The focus of the study is relevant to the field of mass casualty incident management and disaster, as proper communication is extremely relevant in the management of catastrophes.MethodThe first phase of the project started with a qualitative methodology SCRUM, for catching the end user’s feedback and requirements to design the interface platform. It was developed a platform to support first responders in disasters areas improving the 3D scanning and analysis of disaster areas. This platform is based on the concepts of intelligence amplification and eXtended Reality, with hololens, drones and robots. The project continued with a β phase in which the platform with all tools integrated were tested in simulated mass casualty disasters.ResultsThese technologies are tested in different disaster scenarios: A flooded subway stop in Stockholm, an accident in the chemical industry in Marseille, and a man-made explosion in a hospital in Madrid. Through this platform, first responders can immediately initiate operations without exposing personnel to potential harmful risks without specialized equipment, with all important information shared and coordinated, among all responders, whether they are security, firefighters, or emergency health professionals.ConclusionsThe performance pilots and the questionnaire results validated the effectiveness and usability of the final version of the INTREPID platform and tools.

The impact of interfacial quality and nanoscale performance disorder on the stability of alloyed perovskite solar cells

AbstractMicroscopy provides a proxy for assessing the operation of perovskite solar cells, yet most works in the literature have focused on bare perovskite thin films, missing charge transport and recombination losses present in full devices. Here we demonstrate a multimodal operando microscopy toolkit to measure and spatially correlate nanoscale charge transport losses, recombination losses and chemical composition. By applying this toolkit to the same scan areas of state-of-the-art, alloyed perovskite cells before and after extended operation, we show that devices with the highest macroscopic performance have the lowest initial performance spatial heterogeneity—a crucial link that is missed in conventional microscopy. We show that engineering stable interfaces is critical to achieving robust devices. Once the interfaces are stabilized, we show that compositional engineering to homogenize charge extraction and to minimize variations in local power conversion efficiency is critical to improve performance and stability. We find that in our device space, perovskites can tolerate spatial disorder in chemistry, but not charge extraction.

010. Ileus Obstruktif Letak Tinggi E.C Susp Hirschprung pada Pasien Umur 22 Tahun di RSUP Prof. Dr IGNG Ngoerah pada Tahun 2023

Background: Hirschsprung is a disease that occurs in the intestine, and cases most often appear in the colon (colon). Symptoms that usually arise are chronic constipation, failure to grow, and malnutrition. The surgical procedure approach that can be performed in this case is by carrying out an exploration laparatomy and placed a colostomy on the patient. Case: A 22-year-old male patient presents to the emergency department with abdominal pain, His pain began suddenly then dissappear gradually, accompanied by flatulence and nausea since a week ago. Other complaints such as fever and vomiting are denied. Patients with a history of defecation patterns every 2-3 days. Patients complain of difficulty defecating since last week before admitted, the stool form was a small amount of liquid, frequency is 2-3x/day. Stool with blood (-), black or tarry stool (-). Patients with a history of circumcision surgery. The results of the examination showed an increase in WBC 15.11. Based on the BOF results, the results described as a leading to paralytic ileus, Fecal material prominent as high as the pelvic cavum. In addition, based on the results of abdominal ultrasound, it is said that most of the scanning areas are covered by prominent intestinal gas, mild fatty liver. After the exploratory laparatomy, no signs of malignancy were found in the patient, but there was suspicion towards Hirschsprung where the patient did not have the flexura hepatica ligament and the lienalis flexura ligament. Conclusion: Hirschsprung requires surgical procedures that must be explained throughly to patient and families. The surgical procedure approach that can be performed in this case is by carrying out an exploratory laparatomy and the placed a colostomy on the patient. And colon in loop will be used to determine and evaluate the intestine height with aganglionic.

Examining the Influence of Season Phase, Age, and Anthropometrics on Body Composition Trends in National Basketball Association Athletes.

Russell, JL, Baker, BS, Mercer, RA, and McLean, BD. Examining the influence of season phase, age, and anthropometrics on body composition trends in NBA athletes. J Strength Cond Res XX(X): 000-000, 2024-This study aimed to describe seasonal body composition changes in NBA athletes using Dual-energy X-ray Absorptiometry (DXA) and to explore the relationship between these changes and factors such as age and anthropometrics. A retrospective analysis was conducted using 402 DXA scans from 62 professional male basketball players, obtained from one NBA team between 2012 and 2023. Seasonal phases were defined as preseason, pre all-star, post all-star, and offseason. A custom region of interest (ROI) method was used to ensure consistent scan areas for taller athletes who exceeded the DXA bed length. Linear mixed models analyzed the influence of seasonal phases, age, and height on lean mass (LM), fat mass (FM), and bone mineral content (BMC). In-season phases (pre all-star and post all-star) showed small increases in LM and decreases in FM compared with the preseason, with no significant BMC changes. Chronological age was associated with increases in LM but not FM. Taller athletes exhibited increases in LM, FM, and BMC. Significant random variance across players and seasons indicated that additional unmeasured factors might influence body composition. NBA athletes generally gain LM and lose FM during the season, with older players showing increased LM gain. The study's novel ROI method provide reliable data for athletes exceeding standard DXA limits, highlighting the importance of tailored body composition assessments in professional basketball. These findings can inform strength and conditioning, nutrition, and player development strategies across different seasonal phases and ages.

Instantaneous Tiltmeter Triggered by Dynamic Wetting Behavior.

A novel instantaneous tiltmeter with dynamic and static monitoring functions is reported that is based on liquid metal dynamic wetting behavior in a bio-fabricated anisotropic microchannel. The proposed system achieves instantaneous tiltmeter functionality, offering a broad detection range (-90°-90°) with high precision (0.05°), a rapid reaction time (0.11 s), and enhanced durability. Moreover, a seamless integration has enabled water wave detection, language programming, and human limb monitoring. Especially, the integration of tiltmeter and a t3D motion platform results in a surface structure scanning system capable of effectively performing large area (>200 cm2) and height difference scanning functions. This innovative approach holds great potential for transformative changes in the fields of advanced manufacturing, flexible robotics, and the flexible sensing, further facilitating widespread adoption.

Clinical Performance of Semi-Automated Spectral-Domain Optical Coherence Tomography Angiography.

Background/Objectives: To evaluate the clinical performance of two optical coherence tomography angiography (OCTA) devices, including a semi-automated device, with respect to image quality and pathology detection, with fluorescein angiography (FA) and indocyanine green angiography (ICGA) serving as the reference standards. Methods: In this prospective cross-sectional study, normal eyes and those with various retinal and choroidal pathologies were enrolled and underwent OCTA scanning using semi-automated 3D OCT-1 Maestro2 and Cirrus™ HD-OCT 5000 devices, as well as FA/ICGA imaging. OCTA scans and FA/ICGA images were independently graded for image quality and the visibility of prespecified anatomic vascular features, along with the presence or absence of pathology on the OCTA scans and the FA/ICGA images (within regions corresponding to the OCTA scan areas). Positive percent agreement (PPA), defined as the proportion of eyes in which the OCTA demonstrated pathology when the corresponding FA/ICGA showed pathology, and negative percent agreement (NPA), defined as the proportion of eyes in which the OCTA showed no pathology when the FA/ICGA also showed no pathology, were calculated. Results: In total, 38 normal eyes and 86 pathologic eyes were enrolled in the study. The majority of images for both devices were considered clinically useful. The PPA and NPA were high for both devices, indicating a good ability to identify disease when present and to rule it out when not present. Conclusions: The findings of this study suggest that the semi-automated Maestro2 and Cirrus have comparably good clinical performance, particularly with regard to accuracy when identifying vascular pathologies.

Revealing the pinning landscape and related vortex pattern evolution in granular superconducting films

Most superconducting electronics based on films exhibit granular structures. It has been suggested that grain boundaries form a network with relatively weak superconductivity, potentially acting as pinning centers. Yet, so far, detailed microscopic studies of the pinning landscape and its relation to vortex behavior remain scarce. Here, we imaged the vortex lattices (VL) in granular Nb films using magnetic force microscopy over large scanning areas at various magnetic fields. A non-monotonic evolution in the degree of vortex lattice ordering was observed with increasing vortex density, driven by a combination of vortex-vortex interactions and pinning effects. The spatial distribution of pinning potential within the film was directly mapped using a recently developed scanning quantum vortex microscope (SQVM). Instead of the network formed by grain boundaries, the pinning landscape presents a network-like structure, yet with domains significantly larger than the individual grains. The results of numerical simulations based on pinning landscape revealed by SQVM well reproduce our experiments. The pinning force per unit length at low magnetic fields was calculated. The critical current density, estimated from the relative positions of vortices, aligns well with the critical state model. Our work illustrates the relationship between the evolution of the vortex lattice with magnetic field and the structural features of granular Nb film, providing new insights into the design of high-performance superconducting electronic devices.

Quantitative analysis of three-dimensional choroidal changes in coronary artery disease patients with swept-source optical coherence tomography angiography

PurposeTo quantitatively analyze three-dimensional (3D) choroidal changes in coronary artery disease (CAD) patients with swept-source optical coherence tomography angiography (SS-OCTA) based on a scan area of 12×12mm. Methods236 CAD patients and 78 controls were included after coronary angiography (CAG) evaluation in this prospective cross-sectional study. Choroidal and foveal avascular zone (FAZ) parameters were compared between the two groups. Choroidal morphological characteristics were also evaluated based on ETDRS quadrants. Receiver operating characteristics (ROC) curves were generated to determine the discriminative power of choroidal and FAZ parameters. Linear regression analysis was used to determine the relationships between Gensini score and choroidal parameters. ResultsChoroidal thickness (CT), choroidal vascular volume/ area (CVV/a), and choroidal stromal volume/ area (CSV/a) were significantly reduced in CAD patients, while 2D vascular density decreased only in 1–6 mm, and no statistical difference in choroidal vascularity index (CVI) values was detected. The AUC values of choroidal parameters were greater in the inner-6 mm area than the outer-6 mm area, and good performance was found with a combination with FAZ parameters (AUC=0.77, P < 0.001). For morphological analysis, both groups showed the greatest values in superior quadrant and the lowest in nasal quadrant. After controlling for confounding factors, Gensini score was negatively associated with CT (β = -0.35, P = 0.003), CVV/a (β = -0.17, P = 0.004), and CSV/a (β = -0.18, P = 0.005). ConclusionThe SS-OCTA provided excellent visualization and quantification of the choroid and showed decreased choroidal thickness and volume in CAD patients, but the morphological features were unchanged. The severity of coronary artery stenosis was independently associated with choroidal changes.

Three-dimensional spatiotemporal wind field reconstruction based on LiDAR and multi-scale PINN

In this numerical study, we use a multi-scale version of physics-informed neural network (PINN) for wind field reconstruction from LiDAR measurements. The reference velocity field is obtained from high-fidelity large-eddy simulation of neutral atmospheric boundary layer, and the LiDAR measurement strategy is restricted to that of a real LiDAR. The multi-scale PINN reconstructs the velocity field by minimizing a combination of the L2-error with respect to the LiDAR measurements and residuals of the governing equations. Our most significant finding is that adding a multi-scale layer to PINN enables us to: (i) capture wider range of scales, (ii) reconstruct the flow field outside the LiDAR scanning area, and (iii) reach faster convergence. We also find that for volumetric flow reconstruction and to deal with uncertainty in the wind direction, the reconstruction accuracy can be greatly improved by employing multiple LiDAR devices. Overall, our results show that the normalized errors in the reconstructed wind field are lower than 5% for all the experiments conducted in this study and that the errors do not increase even in the presence of measurement noise levels of typical LiDAR. These findings show the feasibility of three-dimensional dynamic wind field reconstruction across large wind farms using LiDAR devices.

Stitching accuracy in large area scanning probe microscopy

Stitching accuracy in large area scanning probe microscopy

Optical Coherence Tomography Angiography (OCTA) Study of Microvascular Changes in Systemic Lupus Erythematosus (SLE) Patients with no Clinical Ocular Manifestations

Abstract Purpose The aim of this study is to evaluate retinal microvasculature using OCTA in patients with SLE without signs of retinopathy according to standard lupus retinopathy classification and correlate abnormal vascular density with disease activity and severity. Methods in this Prospective observational non-interventional study, 36 eyes of 18 SLE patients were compared with 36 eyes of normal subjects. The retinal capillary plexuses were examined by OCTA at time of enrollment and every 4 months for a year using Angio-OCT Optovue RTVue XR Avanti system (Optovue Inc., Fairmont, CA) with documentation of Foveal avascular zone (FAZ) area in mm, acircularity index(AI), Retinal vessel density in a 300-μm-wide region around the FAZ (FD-300), Retinal vessel density in superficial and deep retinal layers (foveal, parafoveal and perifoveal areas). The scanning area was captured in 6 × 6-mm sections, automatically centered on the fovea (HD angio retina 6 × 6-mm), also radial peripapillary vessel density (HD angio disc 4.5 × 4.5-mm) (superior, inferior, nasal and temporal) were studied. The disease activity and damage risk were evaluated by the SLEDAI-2 K and SLICC/ACR system and a correlation was done between changes found and disease activity. Results No difference was found between SLE patients and the normal in foveal avascular zone (FAZ) area, FAZ perimeter, Acircularity Index (AI)(P &amp;gt; 0.05). No difference was found between SLE patients’ macular thickness in foveal region and parafoveal region and the normal (P &amp;gt; 0.05),while mean perifoveal average macular thickness was significantly lower in SLE patients group (p = 0.025). There was a significant decrease in foveal thickness measurements in SLE patients group during follow up period (p = 0.007). SLE patients had significantly lower superficial vessel densities (SVD) than normal in the parafoveal and perifoveal regions (p = 0.001),(p &amp;lt; 0.001) respectively, and during follow up period significant decrease was observed in SVD values (p = 0.001). Regarding the deep capillary plexus (DCP), There was no significant difference between SLE patients group and the normal (p &amp;gt; 0.05), while during follow up period Significant decrease was observed in deep foveal vessel density in SLE patients group (p = 0.013). There was a significant negative correlation between disease activity (measured by SLEDAI-2K and SLICC/ACR scores) and SVD &amp; foveal deep vessel density. Conclusions OCTA permits noninvasive quantitative assessment of retinal vessel density in SLE, allowing early detection of altered retinal circulation. superificial Vessel density and foveal deep vessel density could be included in future assessment of SLE activity and damage scores to early detect any changes for early management and treatment.

Prostate magnetic resonance imaging (MRI) in patients with hip implants-presetting a protocol using a phantom.

Metal structures are a source of artifacts that significantly complicate the interpretation of magnetic resonance imaging (MRI). The use of prostate MRI as a preliminary test in men with a suspicion on prostate cancer leads to an increased use of the test. The aim of this study was to solve a clinically significant problem: to ensure the reduction of artifacts from metal hip implants during prostate MRI. Another goal was to evaluate the impact of artifact reduction methods on quantitative measurements. The prostate gland (PG) phantom model was a cylinder filled with an aqueous solution of polyvinylpyrrolidone at the concentrations of 40%, 30%, and 20% [central zone (CZ), peripheral zone (PZ), and "lesion", respectively]. Phantom MRI study was conducted on Philips Ingenia 1.5T and Philips Ingenia 3T scanners. For 1.5 T, the reduction in the influence of artifacts inside region of interest (ROI) was observed, expressed in a decrease in the average apparent diffusion coefficient (ADC) (CZ, PZ, "lesion") for the manual artifact reduction (MAR) and ZOOM (title of software artifact reduction) techniques compared to the standard method. For 3T this effect was not detected. The same ADC results were obtained for Standard and MAR techniques, and increased ADC values for ZOOM. Despite the fact that the spread of ADC values on 3.0T scanners was minimal, there was a significant deviation of ADC values from the reference ones (up to 30.4%). Therefore, it is necessary to use a correction coefficient in the ADC calculation for the 3.0 T device. In the presented clinical case, high-quality tomograms were obtained without any artifacts, despite the presence of two hip replacement devices in the scanning area. The accurate prostate MRI in the presence of implants is essential for an accurate diagnosis. This approach allows to reduce artifacts from hip implants, to visualize PG and periprostatic tissue in the best way, and to detect malignant and benign changes.

Reference-Based OCT Angiogram Super-Resolution With Learnable Texture Generation.

Optical coherence tomography angiography (OCTA) can visualize retinal microvasculature and is important to qualitatively and quantitatively identify potential biomarkers for different retinal diseases. However, the resolution of optical coherence tomography (OCT) angiograms inevitably decreases when increasing the field-of-view (FOV) given a fixed acquisition time. To address this issue, we propose a novel reference-based super-resolution (RefSR) framework to preserve the resolution of the OCT angiograms while increasing the scanning area. Specifically, textures from the normal RefSR pipeline are used to train a learnable texture generator (LTG), which is designed to generate textures according to the input. The key difference between the proposed method and traditional RefSR models is that the textures used during inference are generated by the LTG instead of being searched from a single reference (Ref) image. Since the LTG is optimized throughout the whole training process, the available texture space is significantly enlarged and no longer limited to a single Ref image, but extends to all textures contained in the training samples. Moreover, our proposed LTGNet does not require an Ref image at the inference phase, thereby becoming invulnerable to the selection of the Ref image. Both experimental and visual results show that LTGNet has competitive performance and robustness over state-of-the-art methods, indicating good reliability and promise in real-life deployment. The source code is available at https://github.com/RYY0722/LTGNet.

Sewage sludge ash as filler in asphalt mastic: Low-temperature towards high-temperature performance

The sewage sludge ash (SSA) is characterized as a by-product used in the pavement industry to mitigate the environmental risks, enhance the landfill capacity and conserve the non-renewable resources. This research utilized SSA as a filler substitute in asphalt mastic, and its performance-based properties from low towards high temperatures were evaluated. For this goal, the physical and chemical properties of SSA and rock powder (used as base filler) were determined using BET surface area measurement, X-ray fluorescence, and scanning electron microscopy tests. The performance of base and SSA-modified asphalt mastics in four filler/bitumen weight ratios (0.6, 0.8, 1, and 1.2) was investigated using dynamic shear rheometer, multiple stress creep and recovery, linear amplitude sweep, and bending beam rheometer tests across a wide temperature range. The results indicate that SSA has a higher specific surface area, better bitumen absorption, and lower density compared to the base filler. Additionally, unlike the acidic nature of the base filler, SSA possesses strong basic properties, leading to a stronger chemical bond with bitumen and enhanced resistance to aging, particularly at high temperatures. Moreover, the lower density of SSA escalates the amount of filler per unit volume of the SSA-modified asphalt mastic, leading to the increased stiffness and elasticity. This trend improves resistance to permanent deformation and cracking at medium temperatures, although it has an adverse effect on performance of mastic at low temperatures. Moreover, due to the improved performance of SSA-modified asphalt mastic, this study can contribute to the sustainable development of the pavement industry.

IMPACT OF THE WALL-PARALLEL LENGTH SCALE OF ROUGHNESS ON THE DEVELOPMENT OF TURBULENT BOUNDARY LAYERS IN TURBINES

Abstract The detrimental effects of surface roughness on turbulent boundary layers in turbines, and compressors, are well known. Prediction can be problematic, especially for surfaces which are not similar to sand grains. Several publications have proposed additional parameters, slope, skew, etc. to augment a wallnormal measure. Here, we introduce a new roughness parameter, the mean separation, which explicitly measures the average separation between each local minima and its closest local maxima. Scans of turbine blade surfaces have mean separations which are up to six times that of the sand grain surface with the same wallnormal measure. High resolution, &amp;lt; 0.1 μm, area scanning tools and 3-D printing techniques have enabled the development of a “Scan-Scale-Print-Measure” methodology. A surface scan is scaled-up, 3-D printed, applied to a flat-plate and then the turbulent boundary layer is measured. The methodology has enabled parametric studies where the mean separation was increased whilst keeping either the wallnormal or the feature size constant. Both studies demonstrated a surface roughness-loss that was strongly dependent on the mean separation and different to a sand grain correlation. It also showed that for large mean separations the roughness-loss decreased to zero. A study into pits-and-peaks showed that, at the same wallnormal, peaks generated a roughness-loss twice that of pits. An engine representative surface produced only half the roughness-loss that would be attributed to a sand grain surface. The roughness loss was estimated within 5% using the parametric studies.