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Advancing lane formation and high-density simulations in bidirectional flow: a humanoid pedestrian model incorporating gait dynamics and body rotation
Get PDFCurrent bidirectional pedestrian flow models face challenges in accurately simulating lane formation and high-density conditions. This study addresses these issues by developing an improved humanoid pedestrian model (HPM), which extends the applicability of the original HPM from one-dimensional to two-dimensional scenarios and offers a more realistic simulation of pedestrian behavior. The improved HPM incorporates two distinct gaits—walking while rotating and walking while turning, which capture the complex dynamics of human walking—and an innovative gait-planning process. Additionally, a novel energy-based heuristic rule that considers factors such as deviation from the target direction, body rotation to navigate gaps, and reduced walking velocity is introduced. The energy expression is designed according to the form of mechanical energy, with no parameters requiring calibration. This design enables our model to demonstrate, to some extent, that pedestrians determine their walking direction by minimizing mechanical energy consumption. Simulations are conducted under conditions replicating previous experiments to validate the improved HPM against both experimental results and two classic models, namely the heuristic-based model and the social force model. The improved HPM shows minimal trajectory deviation; effectively replicates body rotation that facilitates efficient lane formation; and transitions swiftly from a randomized flow to stable, well-ordered flow patterns. Moreover, the improved HPM achieves a maximum density of 7 ped/m2, representing a significant advancement in modeling high-density scenarios. Overall, the improved HPM offers deep insights into the crowd dynamics of bidirectional flow and thereby improves the accuracy of simulations in high-density situations.published_or_final_versio
Childhood Maltreatment Experience Within a Patriarchal and Islamic Religious Context: Impacts on Dependent Self-Image of Salar Muslim Women
No full textWomen who have experienced maltreatment in childhood may be more susceptible to developing a dependent self-image, which can impede their overall well-being and sense of agency. This issue is particularly prevalent among the Salar Muslim women of China, who belong to a national minority and are subject to gender-based oppression within a patriarchal society, with additional challenges within the context of Islamic society. The aims of the current study are twofold: (a) It aims to examine the relationship between patriarchal and religious beliefs and dependent self-image among this often-overlooked population in China—Salar Muslim women. (b) It aims to examine the relationship between childhood maltreatment and the dependent self-image among Salar Muslim women. Two hundred one married Salar Muslim women with a probability proportional to the size sampling approach were recruited in the quantitative survey (Mage = 34.46, SD = 9.58). Multilevel random effects regression models were conducted. The findings indicate that patriarchal beliefs and intrinsic religious motivation were significantly associated with dependent self-image. Moreover, experiences of childhood maltreatment are found to be significantly associated with dependent self-images in this group, even after accounting for contextual factors such as patriarchal beliefs, religious motivations, and other relevant covariates. This study enhances our understanding of how childhood maltreatment impacts the development of a dependent self-image among women, particularly within the complexities of a patriarchal and Islamic cultural setting. We recommend that future research adopts a more nuanced perspective on women’s self-image development, considering the interplay of childhood experiences and sociocultural contexts
The topicalization of culture in Cambridge undergraduate admissions interviews
Get PDFAbstract: This article explores how candidates discuss cultural topics that overlap with their sociocultural background during the Cambridge undergraduate admissions interviews, an academic gatekeeping encounter. On the one hand, discussion of this kind can be a source of epistemic authority for these candidates. On the other hand, such an affordance does not insulate them from the intercul- tural phenomena we see attested in other encounters, such as job interviews. Candidates may attempt to signal likeminded sociocultural values to their in- terviewers, typically by disassociating themselves from the stigmatic aspects of their sociocultural background. Less commonly, interviewers may also engage in foreignizing behaviour. Interactional data from three interviews are used to exemplify how the imbrication of interculturality and institutional power patterns out in different ways, and how this impacts the evaluative outcomes of the can- didates in question.摘要: 本文探討考生如何在劍橋大學本科生入學面試這個學術把關環節(gatekeeping encounter) 中討論與自身社會文化背景相關的文化議題。一方面,相關討論可作考 生認知權威 (epistemic authority) 的來源。另一方面,此權威的可供性並不將考生與 在其他把關情節(如工作面試)中發生的跨文化現象隔離。考生可嘗試向面試官 表達志同道合的社會文化價值,如將自己從其文化背景被污名化的一面分離。在 不常見的情況下,面試官亦有可能參與異化 (foreignizing) 的行爲。本文將通過三 個面試中的互動數據舉例説明跨文化性 (interculturality) 和機構權力的重叠如 何以多種方式發生並影響考生的評核結果。published_or_final_versio
Alchemy of Conceptualization: An Illustration of a Multi-Family Therapy (MFT) for Hong Kong Families Adapting to Brace Treatment for Adolescent Idiopathic Scoliosis
No full textEnhancing bone regeneration through 3D printed biphasic calcium phosphate scaffolds featuring graded pore sizes
No full textHuman long bones exhibit pore size gradients with small pores in the exterior cortical bone and large pores in the interior cancellous bone. However, most current bone tissue engineering (BTE) scaffolds only have homogeneous porous structures that do not resemble the graded architectures of natural bones. Pore-size graded (PSG) scaffolds are attractive for BTE since they can provide biomimicking porous structures that may lead to enhanced bone tissue regeneration. In this study, uniform pore size scaffolds and PSG scaffolds were designed using the gyroid unit of triply periodic minimal surface (TPMS), with small pores (400 μm) in the periphery and large pores (400, 600, 800 or 1000 μm) in the center of BTE scaffolds (designated as 400-400, 400–600, 400–800, and 400–1000 scaffold, respectively). All scaffolds maintained the same porosity of 70 vol%. BTE scaffolds were subsequently fabricated through digital light processing (DLP) 3D printing with the use of biphasic calcium phosphate (BCP). The results showed that DLP 3D printing could produce PSG BCP scaffolds with high fidelity. The PSG BCP scaffolds possessed improved biocompatibility and mass transport properties as compared to uniform pore size BCP scaffolds. In particular, the 400–800 PSG scaffolds promoted osteogenesis in vitro and enhanced new bone formation and vascularization in vivo while they displayed favorable compressive properties and permeability. This study has revealed the importance of structural design and optimization of BTE scaffolds for achieving balanced mechanical, mass transport and biological performance for bone regeneration
Automatic tiny crack positioning and width measurement with parallel laser line-camera system
No full textQuantifying tiny cracks is crucial for assessing structural conditions. Traditional non-contact measurement technologies often struggle to accurately measure tiny crack widths, especially in hard-to-access areas. To address these challenges, this study introduces an image-based, handheld parallel laser line-camera (PLLC) system designed for automated tiny crack localization and width measurement from multiple angles and safe distances. Established by processing parallel laser strips, the camera coordinate system addresses crack positioning and pixel scale distortion challenges typical in non-perpendicular photography. The determined pixel scale enables accurate width measurement. An improved U-Net model automatically identifies crack pixels, enhancing detection accuracy. Additionally, the newly developed Equal Area algorithm enables the sub-pixel width measurement of tiny cracks. Comprehensive laboratory and field testing demonstrates the system's accuracy and feasibility across various conditions. This PLLC system achieves quantitative tiny crack detection in one shot, significantly enhancing the efficiency and utility of on-site inspections.</p
Privacy-preserving coordinated operation of cross-enterprise data centers
No full textAs critical digital infrastructures, data centers are often built with idle computing resources to reliably support large amounts of computational workload. The utilization of those idle resources is restricted by affiliations of data centers and can be enhanced if we allocate workload coordinately to data centers of different enterprises. Besides, conventional centralized optimization, collecting detailed information of data center status as boundaries, cannot be adopted here due to privacy concerns. Considering these issues, this paper presents a privacy-preserving coordinated operation tailored for cross-enterprise data centers. This approach integrates the alternating direction method of multipliers (ADMM) and homomorphic encryption within a distributed algorithm, ensuring privacy-preserving collaborated optimization. To appropriately distribute interests within the operation, a quotation mechanism inspired by the Vickrey–Clarke–Groves (VCG) mechanism is introduced. Case studies verify that the proposed framework significantly reduces the total actual cost by 37.58% under a specific workload level. The cost reduction or net profit for each participating enterprise is also guaranteed, validating the efficacy and practicality of the proposed framework.</p
Pre-industrial Common Era temperature fluctuations in South China inferred based upon bacterial tetraether lipids from Lake Poyang
No full textQuantifying past temperature changes during the Common Era (the past 2000 years) is essential for assessing the rates, magnitudes, and consequences of different climate forcings on current warming and projecting future climate change. At present, however, the quantitative evaluation of temperature changes at multi-centennial-to-millennial timescales remains not well understood. In this study, we provide a high-quality mean annual temperature record for the past 2000 years based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) in a well-dated sediment core retrieved from Lake Poyang in the middle and lower reaches of the Yangtze River. Our results show an overall pre-industrial cooling trend in the Poyang Lake region, with clear temperature changes associated with the Medieval Warm Period (MWP) and Little Ice Age (LIA), consistent with local, regional, and global records. The centennial to millennial temperature fluctuations, particularly the pronounced cooling at approximately 1500 CE, generally agrees with changes in total solar irradiance, supporting the importance of solar activity in affecting pre-industrial temperature changes. Further comparisons with other biomarker-based quantitative temperature reconstructions revealed that the temperature offset between the MWP and LIA increased with latitude and elevation, suggesting that centennial-scale temperature fluctuations were amplified at higher elevations and latitudes during the past two millennia.</p
Enhanced Mechanical Properties in Bulk Nanograined Ni with High-Density Fivefold Twins
No full textFivefold twins are extensively present in nanoparticles and nanowires, enhancing their performance in physical, chemical, and mechanical properties. However, a deep insight into the correlation between mechanical properties and fivefold twins in bulk nanograined materials is lacking due to synthesis difficulties. Here, a bulk fivefold-twinned nanograined Ni is synthesized via electrodeposition. The fivefold-twinned nanograins typically feature decahedral and icosahedral shapes similar to fivefold-twinned particles. The material exhibits a yield strength of ≈1.7 GPa under both compression and tension. Tensile samples achieve an ultimate strength of 2.15 GPa with 15% elongation to failure. The plastic deformation is accommodated by partial dislocation sliding on twin boundaries, splitting fivefold twins, and abnormally refining grains. The size dependence of nucleation stress for partial dislocation is responsible for strengthening and strain hardening. The results showcase the potential of incorporating fivefold twins into bulk nanocrystalline materials to tailor mechanical properties and applications across diverse fields.</p
A dexterous and compliant aerial continuum manipulator for cluttered and constrained environments
No full textAerial manipulators can manipulate objects while flying, allowing them to perform tasks in dangerous or inaccessible areas. Advanced aerial manipulation systems are often based on rigid-link mechanisms, but the balance between dexterity and payload capacity limits their broader application. Combining unmanned aerial vehicles with continuum manipulators emerges as a solution to this trade-off, but these systems face challenges with large actuation systems and unstable control. To address these challenges, we propose Aerial Elephant Trunk, an aerial continuum manipulator inspired by the elephant trunk, featuring a small-scale quadrotor and a dexterous, compliant tendon-driven continuum arm for versatile operation in both indoor and outdoor settings. We develop state estimation for the quadrotor using an Extended Kalman Filter, shape estimation for the continuum arm based on piecewise constant curvature, and whole-body motion planning using minimum jerk principles. Through comprehensive fundamental verifications, we demonstrate that our system can adapt to various constrained environments, such as navigating through narrow holes, tubes, or crevices, and can handle a range of objects, including slender, deformable, irregular, or heavy items. Our system can potentially be deployed in challenging conditions, such as pipeline maintenance or electricity line inspection at high altitudes.</p