Characteristics Of Vessels Research Articles

Automatic Evaluating of Multi-Phase Cranial CTA Collateral Circulation Based on Feature Fusion Attention Network Model.

Stroke is one of the main causes of disability and death, and it can be divided into hemorrhagic stroke and ischemic stroke. Ischemic stroke is more common, and about 8 out of 10 stroke patients suffer from ischemic stroke. In clinical practice, doctors diagnose stroke by using computed tomography angiography (CTA) image to accurately evaluate the collateral circulation in stroke patients. This imaging information is of great significance in assisting doctors to determine the patient's treatment plan and prognosis. Currently, great progress has been made in the field of computer-aided diagnosis technology in medicine by using artificial intelligence. However, in related research based on deep learning algorithms, researchers usually only use single-phase data for training, lacking the temporal dimension information of multi-phase image data. This makes it difficult for the model to learn more comprehensive and effective collateral circulation feature representation, thereby limiting its performance. Therefore, combining data for training is expected to improve the accuracy and reliability of collateral circulation evaluation. In this study, we propose an effective hybrid mechanism to assist the feature encoding network in evaluating the degree of collateral circulation in the brain. By using a hybrid attention mechanism, additional guidance and regularization are provided to enhance the collateral circulation feature representation across multiple stages. Time dimension information is added to the input, and multiple feature-level fusion modules are designed in the multi-branch network. The first fusion module in the single-stage feature extraction network completes the fusion of deep and shallow vessel features in the single-branch network, followed by the multi-stage network feature fusion module, which achieves feature fusion for four stages. Tested on a dataset of multi-phase cranial CTA images, the accuracy rate exceeding 90.43%. The experimental results demonstrate that the addition of these modules can fully explore collateral vessel features, improve feature expression capabilities, and optimize the performance of deep learning network model.

An expanding mechanical role for the tiny mammalian endolymphatic duct: 1. Modification of Békésy model is specifically needed to cope with ambient pressure variation—with weather, altitude or ocean depth

von Békésy’s pioneering work and two-chamber model with basilar membrane (BM) separating the perilymph chambers was a first-pass assumption which worked to explain basic frequency-band analysis. Yet it did not cover psychoacoustical phenomena. Nor did it cover the repeated demonstrations by this author of baseline displacements of the BM, nor mysterious changes in the volume of the tiny endolymphatic duct—even in human ears with normal thresholds. Since 2009 the duct has been shown to possess all the necessary characteristics of a pressure vessel, viz., it is lined with aquaporins and tight junctions while the cells of the stria vascularis maintain a strict osmotic gradient. We submit that such evolutionary change was necessary because ambient pressure changes are too large to be corrected by passive equalization and need to be actively eliminated to preserve hearing sensitivity. Any theory must cover marine mammals which have adapted to ocean pressures measured in megapascals. In this case, infrasound is modelled as a varying pressure pedestal which must be cancelled. This video presentation covers one possible mechanical configuration for how such a cancelation might be achieved—a hypothesized feedback control system utilizing outer hair cell somatic motility plus our previously-modelled otolith-based pressure transducer.

POST-IVUS: A perceptual organisation-aware selective transformer framework for intravascular ultrasound segmentation.

Intravascular ultrasound (IVUS) is recommended in guiding coronary intervention. The segmentation of coronary lumen and external elastic membrane (EEM) borders in IVUS images is a key step, but the manual process is time-consuming and error-prone, and suffers from inter-observer variability. In this paper, we propose a novel perceptual organisation-aware selective transformer framework that can achieve accurate and robust segmentation of the vessel walls in IVUS images. In this framework, temporal context-based feature encoders extract efficient motion features of vessels. Then, a perceptual organisation-aware selective transformer module is proposed to extract accurate boundary information, supervised by a dedicated boundary loss. The obtained EEM and lumen segmentation results will be fused in a temporal constraining and fusion module, to determine the most likely correct boundaries with robustness to morphology. Our proposed methods are extensively evaluated in non-selected IVUS sequences, including normal, bifurcated, and calcified vessels with shadow artifacts. The results show that the proposed methods outperform the state-of-the-art, with a Jaccard measure of 0.92 for lumen and 0.94 for EEM on the IVUS 2011 open challenge dataset. This work has been integrated into a software QCU-CMS2 to automatically segment IVUS images in a user-friendly environment.

The Combination of Black Hat Transform and U-Net in Image Enhancement and Blood Vessel Segmentation in Retinal Images

Diabetic Retinopathy (DR) is a disorder of the eye caused by damage to blood vessels in the retina. Damage to the retinal blood vessels can be analyzed by segmenting the blood vessels on the image. This study proposes a combination of image enhancement and blood vessel segmentation in retinal images. Retinal image enhancement is carried out using the black hat transform method to obtain a detailed view of blood vessels in retinal images. Segmentation of blood vessels in retinal images is carried out using the U-Net architecture. The results of image enhancement are measured using MSE and PSNR. This study has an MSE value below 0.05 and a PSNR above 90dB. The MSE and PSNR values obtained show that the black hat transform method is very good at image enhancement. Segmentation has an accuracy value above 0.95 and a sensitivity value above 0.85. In addition, the specificity value and f1-score are above 0.8. This shows that the proposed stages of image enhancement and blood vessel segmentation are able to accurately recognize blood vessel features in retinal images.

The Design and Characteristics of White Porcelain Vessels for Royal Marriage Ceremonies in Late Chosŏn: porcelain jar with dragon design in underglaze cobalt blue with inscription of chŏnjiugimssijason(傳之于金氏子孫) at the British Museum

The aim of this study is to analyze the designs of <i>chujun</i>(rice wine jar) and <i>hwajun</i>(flower vase), white porcelain vessels used in Chosŏn’s royal marriage ceremonies, and to identify how their use differed according to the status of the person being married. Furthermore, I propose the circumstances under which the <i>paekchayongjun</i>(white porcelain jar with dragon design) stored at the British Museum was produced. <i>paekchach’ŏnghwajuhae</i>, a type of white porcelain jar for rice wine with decoration of dragons in underglaze cobalt blue, stands out among white porcelain vessels used in royal marriages as it was reserved for the king or the crown prince. Those made in late Chosŏn are taller than fifty centimeters in height and decorated with a design of two dragons with five toenails, foliage patterns around the mouth, palm leaf patterns around the shoulders, and lotus petal patterns at the bottom. Originally, the use of blue and white porcelain had not been granted for the marriage of princes and princesses who were not heirs to the throne, but <i>ch’ŏnghwayonghwajun</i>, a type of white porcelain jar with the decoration of dragons in underglaze cobalt blue was permitted as flower vases in the early eighteenth century(1721-1753). However, as King Yŏngjo increasingly advocated frugality, <i>ch’ŏnghwayonghwajuns</i> were replaced with simple white porcelain in 1764, marking the latest date for <i>ch’ŏnghwayonghwajuns</i>. The surviving examples of <i>ch’ŏnghwayonghwajun</i> are almost identical in pattern to paekchach’ŏnghwajuhaes, but are smaller in size — about thirty centimeters tall — and the dragons only have four toenails. Based on evidences, I propose that the jar stored at the British Museum was likely used at the wedding of Princess Hwasun and Kim Hanshin in 1732, the eighth year of King Yŏngjo’s reign. This vessel likely represents the King’s wishes for the birth of grandchildren by the princess, and was inherited by her descendants, Kim I-ju, Kim Noyŏng, Kim Nogyŏng, and Kim Jŏnghŭi.

A feast: Indigenous production and interregional exchange reflected by the bronze vessels unearthed from Shuangyuan Village Cemetery in southwestern China

AbstractSurprising combinations of bronze vessels with multiple cultural elements have been unearthed in Shu tombs in southwestern China, indicating a significant connection with the middle and lower reaches of the Yangtze River. However, there is currently no comprehensive evidence for the provenance of these foreign style vessels, and little emphasis has been given to the diachronic changes in the interaction between Shu culture and its surroundings. This article investigates the bronze vessels unearthed from the Shuangyuan Village Cemetery in Chengdu during the Eastern Zhou Dynasty and aims to deeply reveal the production and exchange of bronze vessels unearthed from Shuangyuan Village Cemetery from the perspective of lead sources through typological analysis and scientific analysis. The study clarified the ages of the local style Shu culture vessels and foreign style vessels, and the latter exhibited a strong influence of the Chu and Yue cultures. Lead isotope analysis shows that the lead source characteristics of foreign style vessels are consistent with those of vessels from Chu‐Yue culture at the same time, and they may be imported from Chu directly. The specific interaction modes of Shu and Chu underwent a clear transformation during the middle Warring States period.

Study of the influence of the vessel stern shape on its hydrodynamic characteristics

Determining the main dimensions of the small vessels while designing is an important and difficult task due to the large number of mutually exclusive factors affecting the hydrodynamic characteristics of such vessels. The existing patterns for determining the length, width and draft of small vessels are quite general. This complicates their usage for the vessel of a specific design. In this case, it is necessary to check technical solutions, one of the ways that may be implied is the usage of computational fluid dynamics (CFD) methods. This paper presents the results of the numerical simulation of boat movement in the transient mode with Froude numbers up to 1.2. The process of preparation and numerical modeling of the aerodynamics of a composite wing in the NUMECA/FineMarineTM software package is described, the choice of the turbulence model and the parameters of the computational grid, including the resolution of the boundary layer, is justified. The study of the influence of three variants of the width and shape of the aft tip on the change in draft, trim angle, wetted surface and resistance of the boat is carried out. An increase in the width of the flat planing part of the aft tip has a favorable effect on the hydrodynamic characteristics of a small vessel, even when moving in transition mode at L/B from 3.5 to 3.99. At the same time, the use of the extension of the underwater part of the aft tip requires a more detailed study.

Hardwood vessel-inspired chitosan-based sponge with superior compressibility, superfast adsorption and remarkable recyclability for microplastics removal in water

Microplastics (MPs) in water that are hazardous and recalcitrant pose formidable risks for human health, necessitating the development of efficient, sustainable removal methods. This study introduces a chitosan/bacterial cellulose sponge with superior compressibility and remarkable recyclability for polystyrene (PS) MPs rapid adsorption, inspired by the robustness and directional, rapid nutrient transport characteristics of hardwood vessels. The unique structure of sponge, featuring tunable oriented cellular channels and strong walls, is achieved via temperature-controlled directional freezing and double cross-linking. This structure enables the sponge to maintain high wet compressive reversibility, with a retention rate of 94.9% after 100 compression cycles. Moreover, the as-prepared sponge demonstrates a high MPs adsorption capacity of 0.26 mg·g−1. Owing to its excellent wet compressibility and adsorption performance, the sponge demonstrates remarkable cycling removal efficiency of 47.30% after 20 cycles. The experimental results together with theoretical fitting provide insight into how the hardwood-like structure and active sites of Chitosan enhance MPs adsorption. This work advances the development of efficient and sustainable MPs removal technologies using biomimetic and high-performance adsorbents and expands the insight into the MPs adsorption mechanism by chitosan-based sponge.

An MRI study of lateral vascular safety zones in oblique lumbar interbody fusion surgery

To study the anatomical characteristics of blood vessels in the lateral segment of the vertebral body through the surgical approach of oblique lumbar interbody fusion (OLIF) using MRI imaging, and evaluate its potential vascular safety zone. The lumbar MRI data of 107 patients with low back and leg pain who met the selection criteria between October 2019 and November 2022 were retrospectively analyzed. The vascular emanation angles, vascular travel angles, and the length of vessels in the lateral segments of the left vertebral body of L 1-L 5, as well as the distance between the segmental vessels in different Moro junctions of the vertebral body and their distances from the edges of the vertebrae in the same sequence (bottom marked as I, top as S) were measured. The gap between the large abdominal vessels and the lateral vessels of the vertebral body was set as the lateral vascular safe zones of the lumbar spine, and the extent of the safe zones (namely the area between the vessels) was measured. The anterior 1/3 of the lumbar intervertebral disc was taken as the simulated puncture center, and the area with a diameter of 22 mm around it as the simulated channel area. The proportion of vessels in the channel was further counted. In addition, the proportions of segmental vessels at L 5 without a clear travel and with an emanation angel less than 90° were calculated. Except for the differences in the vascular emanation angles between L 4 and L 5, the vascular travel angles between L 1, L 2 and L 4, L 5, and the length of vessels in the lateral segments of the vertebral body among L 1-L 4 were not significant ( P>0.05), the differences in the vascular emanation angles, vascular travel angles, and the length of vessels between the rest segments were all significant ( P<0.05). There was no significant difference in the distance between vessels of L 1, L 2 and L 2, L 3 at Moro Ⅰ-Ⅳ junctions ( P>0.05), in L 3, L 4 and L 4, L 5 at Ⅱ and Ⅲ junction ( P>0.05). There was no significant difference in the vascular distance of L 2, L 3 between Ⅱ, Ⅲ junction and Ⅲ, Ⅳ junction, and the vascular distance of L 3, L 4 between Ⅰ, Ⅱ junction and Ⅲ, Ⅳ junction ( P>0.05). The vascular distance of the other adjacent vertebral bodies was significant different between different Moro junctions ( P<0.05). Except that there was no significant difference in the distance between L 2I and L 3S at Ⅰ, Ⅱ junction, L 3I and L 4S at Ⅱ, Ⅲ junction, and L 2I and L 3S at Ⅲ, Ⅳ junction ( P>0.05), there was significant difference of the vascular distance between the bottom of one segment and the top of the next in the other segments ( P<0.05). Comparison between junctions: Except for the L 3S between Ⅰ, Ⅱ junction and Ⅱ, Ⅲ junction, and L 5S between Ⅰ, Ⅱ junction and Ⅱ, Ⅲ and Ⅲ, Ⅳ junctions had no significant difference ( P>0.05), there were significant differences in the distance between the other segmental vessels and the vertebral edge of the same sequence in different Moro junctions ( P<0.05). The overall proportion of vessels in the simulated channels was 40.19% (43/107), and the proportion of vessels in L 1 (41.12%, 44/107) and L 5 (18.69%, 20/107) was higher than that in the other segments. The proportion of vessels in the channel of Moro zone Ⅰ (46.73%, 50/107) and zone Ⅱ (32.71%, 35/107) was higher than that in the zone Ⅲ, while no segmental vessels in L 1 and L 2 were found in the channel of zone Ⅲ ( χ 2=74.950, P<0.001). Moreover, 26.17% (28/107) of the segmental vessels of lateral L 5 showed no movement, and 27.10% (29/107) vascular emanation angles of lateral L 5 were less than 90°. L 1 and L 5 segmental vessels are most likely to be injured in Moro zones Ⅰ and Ⅱ, and the placement of OLIF channels in L 4, 5 at Ⅲ, Ⅳ junction should be avoided. It is usually safe to place fixation pins at the vertebral body edge on the cephalic side of the intervertebral space, but it is safer to place them on the caudal side in L 1, 2 (Ⅰ, Ⅱ junction), L 3, 4 (Ⅲ, Ⅳ junction), and L 4, 5 (Ⅱ, Ⅲ, Ⅳ junctions).

Flow characteristics of an aquaculture vessel with perforated sideboards at various incidence angles

Flow characteristics of an aquaculture vessel with perforated sideboards at various incidence angles

Pollution prevention of vessels in the greater bay area: A practical contribution of port state control inspection system towards carbon neutralisation using a tree augmented naive bayes approach

Vessel emissions are one of the major emissions sources affecting carbon neutralisation achievement in the Greater Bay Area (GBA). The vessel pollution prevention ability is effective in preventing vessels from discharging mass emissions. Thus, it is of great value to figure out the vessel's performance in pollution prevention in this area. This study develops a data-driven Bayesian network model focusing on vessel performance in pollution prevention in port state control (PSC) inspections in the GBA. The Tree Augmented Naïve and Expectation Maximisation approaches are applied to learn structures and parameters based on the inspection records obtained from January 2015 to September 2022. An analysis can identify key variables with significant effects on vessel performance in pollution prevention and clarify the positive influence and contributions of PSC inspections toward carbon neutralisation achievement. Practical implications are provided to foster port authorities and local governments in the GBA to minimize the vessels with poor pollution prevention performance sailing in this area. The study also identifies the characteristics of vessels with poor performance and proposes valuable suggestions to restrict the inattentive actions of ship owners and stimulate ship owners to put more effort into the improvement of pollution prevention ability. Further, the study reveals the significance of executing efficient and reliable PSC inspections in promoting carbon neutralisation progress.

Ambient black carbon variations and emission characteristics of typical Chinese vessels in the Yangtze River Delta, China.

Black carbon (BC) has a significant impact on air quality, climate change, and human health. Studies on BC from vessel exhaust have been focused on in recent years. To realize the contribution of BC from vessels to ambient air quality, 28 months of BC variation were observed from February 2019 to May 2022, including 3 fishing moratoriums and 2 normal periods. The results showed that the average daily concentration of BC in the fishing moratorium was significantly lower than that in the normal period. The difference proportion of the BC concentration between 370 and 880 nm was calculated over the whole period. As a result, the mean difference value in the fishing moratorium from February to May was 0.06 ± 0.07, and the normal period was -0.02 ± 0.05. The aethalometer model indicated that BC was greatly affected by fossil fuel combustion in the normal period. The effect of vessel emissions on regional BC concentrations was considerable. In addition, 16 PAHs and 21 elements in PM emitted from 24 vessels of different types were sampled and analyzed in Dianshan Lake and the Taipu River. EC accounted for the highest proportion (23.64%) in the sample of small trawlers compared to the emissions from cargo ships with large tonnages. The component profiles of vessel exhaust showed that Zn, As, phenanthrene (Phe), anthracene (Ant), fluoranthene (Fla), and pyrene (Pyr) were the dominant species, although some of these species were mainly recognized as characteristic factors of coal combustion. To improve the accuracy of identifying the vessel source, the diagnostic ratios of Ant/(Ant + Phe), BaA/(BaA + Chr), Phe/Ant, and BaA/Chr were provided, and they exhibited the obvious characteristics of fuel combustion.

Research on High-Speed Catamaran Motion Reduction with Semi-Active Control of Flexible Pontoon

A high-speed catamaran with a suspension system and flexible pontoons to reduce motion is proposed, and the vertical motion characteristics of the vessel are investigated. The results demonstrate that altering the stiffness of the flexible pontoon can significantly alter the motion characteristics of a high-speed vessel when subjected to wave excitation. The maximum relative error between the theoretical and experimental values of the vertical dynamic characteristics of the flexible pontoon, considered as a gas spring, is 10.5%. The vertical force exerted by the pontoon exhibits nonlinear behavior in response to compression, yet displays approximately linear behavior within its primary operational range. The design of the Linear Quadratic Regulator controller, utilizing genetic algorithm optimization, avoids the issue of subjectively setting weight coefficients typically found in traditional control systems. This approach achieves the objective of determining the optimal feedback matrix within specified constraints. Simulation results illustrate that the LQR controller developed using genetic algorithm significantly enhance the semi-active suspension performance compared to the passive suspension system. The Root Mean Square value of the main cabin acceleration is reduced by 85.82%, simultaneously reducing the RMS value of the suspension dynamic travel by 85.03% and the RMS value of the pontoon dynamic displacement by 24.42%. These outcomes thoroughly substantiate the effective reduction in vertical motion, effectively attenuating the motion of high-speed vessels under wave excitation.

Vessel Detection with SDGSAT-1 Nighttime Light Images

The Sustainable Development Goals Science Satellite-1 (SDGSAT-1) Glimmer Imager for Urbanization (GIU) data is very sensitive to low radiation and capable of detecting weak light sources from vessels at night while significantly improving the spatial resolution compared to similar products. Most existing methods fail to use the relevant characteristics of vessels effectively, and it is difficult to deal with the complex shape of vessels in high-resolution Nighttime Light (NTL) data, resulting in unsatisfactory detection results. Considering the overall sparse distribution of vessels and the light source diffusion phenomenon, a novel vessel detection method is proposed in this paper, utilizing the high spatial resolution of the SDGSAT-1. More specifically, noise separation is completed based on a local contrast-weighted RPCA. Then, artificial light sources are detected based on a density clustering algorithm, and an inter-cluster merging method is utilized to realize vessel detection further. We selected three research areas, namely, the Bohai Sea, the East China Sea, and the Gulf of Mexico, to establish a vessel dataset and applied the algorithm to the dataset. The results show that the total detection accuracy and the recall rate of the detection algorithm in our dataset are 96.84% and 96.67%, which is significantly better performance than other methods used for comparison in the experiment. The algorithm overcomes the dataset’s complex target shapes and noise conditions and achieves good results, which proves the applicability of the algorithm.

Therapeutic advances targeting tumor angiogenesis in pancreatic cancer: Current dilemmas and future directions.

Pancreatic cancer (PC) is one of the most lethal malignancies, which is generally resistant to various treatments. Tumor angiogenesis is deemed to be a pivotal rate-determining step for tumor growth and metastasis. Therefore, anti-angiogenetic therapy is a rational strategy to treat various cancers. However, numerous clinical trials on anti-angiogenetic therapies for PC are overwhelmingly disappointing. The unique characteristics of tumor blood vessels in PC, which are desperately lacking and highly compressed by the dense desmoplastic stroma, are reconsidered to explore some optimized strategies. In this review, we mainly focus on its specific characteristics of tumor blood vessels, discuss the current dilemmas of anti-angiogenic therapy in PC and their underlying mechanisms. Furthermore, we point out the future directions, including remodeling the abnormal vasculature or even reshaping the whole tumor microenvironment in which they are embedded to improve tumor microcirculation, and then create therapeutic vulnerabilities to the current available therapeutic strategies.

Study on Energy Efficient Operation by ship's Trim Optimization based on Computational Fluid Dynamics

The prediction and optimization on resistance characteristics of marine vessels are getting important due to maritime environmental pollution, climate changes, impacts on human health near the coastal area and so on. Therefore, several methods were developed to reduce the fuel consumption of the vessel to improve the voyage performance. Among them, the trim optimization method is one of the popular methods to reduce the fuel consumption of ships. Trim optimization can be done by changing the trim by moving the cargo or ballast water and also can be applied on both new and existing ships. Moreover, this method needs not to change any structural arrangement or machinery of the vessels to apply it. Therefore, in this paper, this method was evaluated by using computational fluid dynamics with the help of commercial software Star-CCM+. Firstly, the numerical analysis of resistance data for KRISO Container Ship (KCS) in even keel were carried out and compared with experimental data from the model test to validate the results. After that, the optimum trim values for different service speeds were estimated using the calculated resistances. It is found that trim optimization at various speeds can be an effective and convenient way for vessels to decrease fuel consumption, emission of harmful substances and improve the energy efficiency by reducing the total drag force. Therefore, it could be one of the most practical ways to improve the environmental friendliness for both new and existing ships and also to fulfill the environmental related regulations.

Clinical and Vessel Characteristics Associated With Hard Outcomes After PCI and Their Combined Prognostic Implications.

Background Cardiac death or myocardial infarction still occurs in patients undergoing contemporary percutaneous coronary intervention (PCI). We aimed to identify adverse clinical and vessel characteristics related to hard outcomes after PCI and to investigate their individual and combined prognostic implications. Methods and Results From an individual patient data meta-analysis of 17 cohorts of patients who underwent post-PCI fractional flow reserve measurement after drug-eluting stent implantation, 2081 patients with available clinical and vessel characteristics were analyzed. The primary outcome was cardiac death or target-vessel myocardial infarction at 2 years. The mean age of patients was 64.2±10.2 years, and the mean angiographic percent diameter stenosis was 63.9%±14.3%. Among 11 clinical and 8 vessel features, 4 adverse clinical characteristics (age ≥65 years, diabetes, chronic kidney disease, and left ventricular ejection fraction <50%) and 2 adverse vessel characteristics (post-PCI fractional flow reserve ≤0.80 and total stent length ≥54 mm) were identified to independently predict the primary outcome (all P<0.05). The number of adverse vessel characteristics had additive predictability for the primary end point to that of adverse clinical characteristics (area under the curve 0.72 versus 0.78; P=0.03) and vice versa (area under the curve 0.68 versus 0.78; P=0.03). The cumulative event rate increased in the order of none, either, and both of adverse clinical characteristics ≥2 and adverse vessel characteristics ≥1 (0.3%, 2.4%, and 5.3%; P for trend <0.01). Conclusions In patients undergoing drug-eluting stent implantation, adverse clinical and vessel characteristics were associated with the risk of cardiac death or target-vessel myocardial infarction. Becausethese characteristics showed independent and additive prognostic value, their integrative assessment can optimize post-PCI risk stratification. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04684043. www.crd.york.ac.uk/prospero/. Unique Identifier: CRD42021234748.

Investigation of the variation of vessels around the pancreatic head based on the first jejunal vein anatomy at pancreaticoduodenectomy.

Pancreaticoduodenectomy (PD) for pancreatic cancer carries a high risk of massive intraoperative blood loss. The artery first approach (AFA) prevents blood loss during PD, but the optimal approach is unclear. The first jejunal vein (FJV) often comprises multiple veins and broadly supports venous drainage of the proximal jejunum. Its ligation carries a risk of proximal jejunum congestion. Here we investigated the anatomical characteristics of PD-associated vessels and AFA approach selection based on FJV anatomy. This study included 148 Japanese living donors for liver transplantation. We reviewed their computed tomography images and assessed the anatomical pattern of PD-associated vessels in terms of FJV anatomy. The FJV traveled posterior to the superior mesenteric artery in 128 patients (86.5%, dorsal group) and anterior in 20 (13.5%, ventral group). The predominant draining vein of the inferior pancreaticoduodenal vein was the superior mesenteric vein in the ventral group (87.5%) and the FJV in the dorsal group (97.9%). Compared with the dorsal group, the ventral group had a significantly greater percentage with the superior mesenteric vein ventral to the superior mesenteric artery (30.0% versus 10.9%) and a significantly larger posterior superior pancreaticoduodenal vein diameter (3.2 ± 0.9 versus 2.7 ± 0.6mm, p = 0.0029). These results were validated in patients with pancreatic head cancer. The anatomical characteristics of PD-associated vessels differed significantly between groups defined by FJV anatomy. Understanding the venous anatomy, especially the FJV, could support selection of the best approach in AFA for PD.

Virtual PMM captive tests using OpenFOAM to estimate hydrodynamic derivatives and vessel maneuverability

This study reveals the significance of hydrodynamic derivatives derived at the different Froud number (Fr) in accurately predicting of a vessel's turning-circle maneuvers through solving the maneuvering modeling group (MMG) model. The computed turning-circle diameter showed a good agreement with the model test results, with less than 4% difference observed when using the hydrodynamic derivatives derived at Fr = 0.201. However, at Fr = 0.26, a significant difference was observed, which could be attributed to the use of lower values of maximum sway amplitude ymax and maximum yaw rate rmax′. The hydrodynamic characteristics of a maneuvering vessel may not be fully reflected, with the high displacement of the straight surging motion dominating the results. In this study, a set of virtual planar motion mechanism (PMM) captive tests is numerically conducted on a bare container ship hull model using an open-source code OpenFOAM. The virtual PMM captive test cases involve different maximum sway amplitude, maximum yaw rates, and Fr, achieved by varying sway amplitudes, heading angles, and the carriage speeds, respectively. The obtained numerical results are reconstructed as Fourier series (FS) equations to derive hydrodynamic derivatives employing the single run (SR) method. A system-based method is adopted to predict vessel's turning-circle maneuverability in calm water by employing the MMG mathematical model.

Thermodynamic behaviour and heat transfer characteristics of air vessels in water delivery systems

Air vessels can effectively prevent water hammer caused by pump failure; however, the thermodynamic behaviour and accurate model of air in air vessels are rarely discussed, and an empirical polytropic index of 1.20 is commonly used for air vessel design. This study calculated the polytropic index based on the improved rational heat transfer (RHT) model using the multiphase volume of fluid (VOF) and k-ε turbulence model. The influence of dynamic airflow and heat transfer in the air vessel on the water delivery system pressure was studied. The effects of inlet and outlet flows, initial pressure, and initial air ratio on heat transfer were investigated. The polytropic indices of the expansion and compression processes in this study were between 1.10 and 1.40 and between 1.05 and 1.40, respectively. Curve fitting was applied to analyse the polytropic indices and substituted into the method of characteristics (MOC) for air vessel design. A hydraulic transient simulation of a practical water delivery project was conducted to compare the variable and fixed polytropic indices. The results showed that variable polytropic indices can better describe the dynamic processes of air. Using a fixed index of 1.20 for a low flow rate is risky. By contrast, the system can be optimised at high flow rates.