Compression

压缩
  • 文章类型: Journal Article
    骨支架在组织工程中起着至关重要的作用,特别是在促进自然修复不足的骨再生方面。尽管聚合物骨支架的制造取得了进展,挑战仍然是优化他们的机械弹性。具体来说,关于聚合物骨支架的疲劳行为的研究很少。这项研究调查了孔结构对准静态和循环压缩下聚乳酸(PLA)支架力学性能的影响。使用基于挤出的3D打印以各种设计制造孔隙率为60%的PLA支架:Gygior,Lidinoid,Fischer-Koch,IWP,和Voronoi.结果表明,甲状腺支架具有最高的抗压强度(6.6MPa),其次是Lidinoid,Fischer-Koch,IWP,和Voronoi设计。增加的支柱厚度与更高的压缩强度有关。然而,归一化抗疲劳性显示出不同的模式。虽然支架在低应变振幅下抵抗疲劳循环,在较高的应变下观察到疲劳损伤。Voronoi结构表现出最高的归一化疲劳性能,在85%应变幅度下持续约58,000次循环,其次是甲状腺,Fischer-Koch,Lidinoid,和IWP结构。与支架的最小横截面积相关的不同拓扑结构中的疲劳性能增强。考虑到静态强度和疲劳强度的重要性,甲状腺拓扑结构是整体的首选。
    Bone scaffolds serve a crucial role in tissue engineering, particularly in facilitating bone regeneration where natural repair is insufficient. Despite advancements in the fabrication of polymeric bone scaffolds, the challenge remains to optimize their mechanical resilience. Specifically, research on the fatigue behaviour of polymeric bone scaffolds is scarce. This study investigates the influence of pore architecture on the mechanical performance of poly-lactic-acid (PLA) scaffolds under quasi-static and cyclic compression. PLA scaffolds with a 60% porosity were fabricated using extrusion-based 3D printing in various designs: Gyroid, Lidinoid, Fischer-Koch, IWP, and Voronoi. Results demonstrated that Gyroid scaffolds had the highest compressive strength (6.6 MPa), followed by Lidinoid, Fischer-Koch, IWP, and Voronoi designs. Increased strut thickness was linked to higher compressive strength. However, normalized fatigue resistance showed a different pattern. While scaffolds resisted fatigue cycles at low strain amplitudes, fatigue damage was observed at higher strains. Voronoi structures exhibited the highest normalized fatigue performance, enduring around 58,000 cycles at 85% strain amplitude, followed by Gyroid, Fischer-Koch, Lidinoid, and IWP structures. Enhanced fatigue performance in different topologies correlated with the minimum cross-sectional area of scaffolds. Given the importance of both static and fatigue strength, the Gyroid topology emerges as the superior choice overall.
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  • 文章类型: Journal Article
    多材料长丝的发展使得基于熔丝制造的增材制造能够满足对高性能轻质多功能部件的需求。在这项研究中,聚乳酸(PLA)和丙烯腈丁二烯苯乙烯基长丝,带有磁性铁(MI)的金属增强材料,不锈钢(SS),青铜(Br),铜(Cu),铋(Bi),和钨(W)进行了研究,以阐明它们复杂的加工-结构-性能关系。通过显微镜对3D打印材料的微观结构进行了表征,并进行了分析,以确定金属横截面积百分比和金属增强体之间的关系,聚合物基质,和孔隙度。在平行和垂直于构建方向的方向上进行压缩测试,以评估取向和金属增强对机械性能的影响。3D打印的样本经历了通过打印层或逐层界面断裂,以垂直和平行于打印层施加的载荷。分别。对于Br-PLA,观察到屈服强度对载荷取向的依赖性,Cu-PLA,SS-PLA,双ABS,和W-ABS;然而,MI-PLA和纯ABS样品没有表现出这种敏感性。金属增强也影响压缩屈服强度的大小,MI-PLA和SS-PLA的强度高于Br-PLA和Cu-PLA,而ABS表现出比Bi-ABS和W-ABS更高的强度。这些结果证明了在印刷和应用中考虑取向的重要性,各种金属增强材料之间的权衡,以增加多功能性,以及这些定制的聚合物复合材料用于新型3D打印结构的潜力。
    The development of multi-material filaments has enabled fused filament fabrication-based additive manufacturing to address demand for high-performance lightweight multifunctional components. In this study, polylactic acid (PLA) and acrylonitrile butadiene styrene based filaments with metallic reinforcements of magnetic iron (MI), stainless steel (SS), bronze (Br), copper (Cu), Bismuth (Bi), and Tungsten (W) were investigated to elucidate their complex processing-structure-property relationships. The microstructure of 3D-printed materials were characterized by microscopy and analyzed to determine the metal cross-sectional area percentage and the relationship between metal reinforcement, the polymer matrix, and porosity. Compression testing was conducted in directions parallel and perpendicular to the build direction in order to evaluate the effect of orientation and metal reinforcement on the mechanical properties. 3D-printed specimens experienced either fracture through print layers or layer-wise interfacial rupture for loads applied perpendicular and parallel to the print layers, respectively. A dependence of yield strength on loading orientation was observed for Br-PLA, Cu-PLA, SS-PLA, Bi-ABS, and W-ABS; however, MI-PLA and pure ABS specimens did not exhibit this sensitivity. Metal reinforcement also influenced the magnitude of compressive yield strength, with MI-PLA and SS-PLA demonstrating increased strength over Br-PLA and Cu-PLA, while ABS demonstrated increased strength over Bi-ABS and W-ABS. These results demonstrate the importance of considering orientation in printing and applications, the trade-off between various metallic reinforcements for added multifunctionality, and the potential of these tailored polymer composites for novel 3D-printed structures.
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  • 文章类型: Journal Article
    我们评估了压缩紧身裤与微按摩结合体力活动对患有脂水肿的女性的影响,以前没有治疗,最近没有体重变化。治疗导致所有主观参数的改善,在自发和诱发的疼痛中,在四肢的体积中,在体重没有显著变化的情况下,无论使用时间如何,年龄,多年的疾病,临床阶段,体重指数(BMI)。在未治疗的脂水肿影响的区域,诱发的疼痛没有改善;脚周没有增加。我们发现在下肢多个点评估的皮下脂肪组织(SAT)和皮肤厚度显着减少。建议将微按摩压缩绑腿作为保守治疗的组成部分。提出了一种临床评估诱发疼痛的方法,称为渐进性疼痛检查(PPC),它允许计算称为Ricolfi-Patton评分(RPS)的数值分数,并用于组织的超声评估。该方法简单且可重复,可以在诊断时完成对患者的临床评估,并可以评估各种治疗的效果。甚至只适用于身体的一侧。
    We evaluated the effect of compression leggings with micromassage in association with physical activity on women with lipedema, not previously treated and without recent changes in body weight. The treatment resulted in an improvement in all subjective parameters, in spontaneous and evoked pain, in the volume of the limbs, in the absence of significant changes in body weight, and regardless of the duration of use, age, years of illness, the clinical stage, and body mass index (BMI). Evoked pain did not improve in areas affected by untreated lipedema; foot circumferences did not increase. We found a significant reduction in the thickness of subcutaneous adipose tissue (SAT) and skin evaluated in multiple points of the lower limb. Micromassage compression leggings are proposed as an integral part of conservative treatment. A method is proposed for the clinical evaluation of evoked pain, called the Progressive Pain Check (PPC), which allows for the calculation of a numerical score called the Ricolfi-Patton Score (RPS) and for the ultrasound evaluation of tissues. The method is simple and repeatable and allows for completion of the clinical evaluation of the patient at diagnosis and for an evaluation of the effects of various treatments, even applied to just one side of the body.
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  • 文章类型: Journal Article
    脱水是木薯粉加工的关键步骤。压缩脱水动力学对于理解和设计脱水操作是有用的。该数据集提供了在4至21bar之间的恒定压力下在过滤固结池中测量的脱水动力学,在几个木薯糊状物上(三个批次在两个粒度分布(PSD)上破碎)。数据集包括,对于每个脱水动力学测量,滤液质量,蛋糕高度,数据来估计施加在产品上的压力(即气压,压缩力)作为时间的函数;以及新鲜和脱水木薯以及滤液的水分含量测量。包含注释的python脚本以读取脱水实验文件并绘制动力学此外,该数据集通过包括从六个木薯批次获得的粒度分布(PSD)来扩展其实用性,经过几个方案变体。这些数据对于理解木薯脱水所涉及的现象很有用。它们也是研究人员的宝贵资源,设计师,和运营商设计木薯脱水。
    Dewatering is a critical step in cassava flours processing. Compression dewatering kinetics are useful to understand and design a dewatering operation. The dataset presents dewatering kinetics measured in a filtration-consolidation cell at constant pressure between 4 and 21 bar, on several cassava mashes (three batches fragmented at two particle size distributions (PSDs)). The dataset comprises, for each dewatering kinetic measurement, filtrate mass, cake height, data to estimate the pressure applied on the product (i.e. air pressure, compression force) as a function of time; and the moisture content measurements of the fresh and dewatered cassava and of the filtrate. A commented python script is included to read the dewatering experimental files and plot the kinetics Furthermore, the dataset extends its utility by including particle size distributions (PSDs) obtained from six cassava batches, subjected to several protocol variants. These data are useful for understanding the phenomena involved in cassava dewatering. They also serve as a valuable resource for researchers, designers, and operators to design cassava dewatering.
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  • 文章类型: Journal Article
    点云是利用包括3D位置和属性的无序点的对象或场景的表示。点云模仿自然形态的能力已获得不同应用领域的极大关注,例如虚拟现实和增强现实。然而,点云,尤其是那些代表动态场景或运动物体的人,由于其巨大的数据量,必须有效地压缩。用于动态点云的最新基于视频的点云压缩(V-PCC)标准使用计算昂贵的正态估计将3D点云划分为许多补丁,分割,和细化。面片被投影到2D平面上以应用现有的视频编码技术。该过程通常导致丢失接近度信息和一些原始点。这种损失引起对用户感知产生不利影响的伪像。该方法在块生成前基于形状相似性和遮挡分割动态点云。这种分割策略通过利用点的密度和遮挡来帮助保持点的接近度并保留更多的原始点。实验结果证明,对于几个基准视频序列的几何和纹理数据,该方法在率失真性能和主观质量测试方面明显优于V-PCC标准和其他相关方法。
    A point cloud is a representation of objects or scenes utilising unordered points comprising 3D positions and attributes. The ability of point clouds to mimic natural forms has gained significant attention from diverse applied fields, such as virtual reality and augmented reality. However, the point cloud, especially those representing dynamic scenes or objects in motion, must be compressed efficiently due to its huge data volume. The latest video-based point cloud compression (V-PCC) standard for dynamic point clouds divides the 3D point cloud into many patches using computationally expensive normal estimation, segmentation, and refinement. The patches are projected onto a 2D plane to apply existing video coding techniques. This process often results in losing proximity information and some original points. This loss induces artefacts that adversely affect user perception. The proposed method segments dynamic point clouds based on shape similarity and occlusion before patch generation. This segmentation strategy helps maintain the points\' proximity and retain more original points by exploiting the density and occlusion of the points. The experimental results establish that the proposed method significantly outperforms the V-PCC standard and other relevant methods regarding rate-distortion performance and subjective quality testing for both geometric and texture data of several benchmark video sequences.
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  • 文章类型: Journal Article
    随着更高的时空分辨率触觉传感系统正在开发用于假肢,可穿戴设备,和其他生物医学应用,它们需要更快的采样率并生成更大的数据流。稀疏的转换可以通过压缩实现压缩采样和高效的数据存储来缓解这些要求。然而,关于触觉交互的最佳稀疏化转换的研究还很滞后。在这项工作中,我们构建了一个正交和双正交小波变换库,作为触觉交互的稀疏变换,并比较了它们在压缩和稀疏性方面的权衡。我们在公开可用的高密度触觉对象抓取数据集(548传感器触觉手套,抓住26个对象)。此外,我们研究了小波变换-1D,2D,或3D-最好压缩这些触觉交互。我们的结果表明,小波变换在压缩触觉数据方面非常有效,并且可以导致非常稀疏和紧凑的触觉表示。此外,我们的结果表明,一维变换实现了最稀疏的表示,其次是3D,最后是2D。总的来说,用于粗略逼近的最佳小波是在时间上评估的Symlet4,它可以稀疏到0.5%的稀疏性,并将10位触觉数据压缩到平均每像素0.04位。未来的研究可以利用本文的结果来帮助大型触觉阵列的压缩采样,并释放计算资源,以便在计算受限的移动平台(如神经假体)上进行实时处理。
    As higher spatiotemporal resolution tactile sensing systems are being developed for prosthetics, wearables, and other biomedical applications, they demand faster sampling rates and generate larger data streams. Sparsifying transformations can alleviate these requirements by enabling compressive sampling and efficient data storage through compression. However, research on the best sparsifying transforms for tactile interactions is lagging. In this work we construct a library of orthogonal and biorthogonal wavelet transforms as sparsifying transforms for tactile interactions and compare their tradeoffs in compression and sparsity. We tested the sparsifying transforms on a publicly available high-density tactile object grasping dataset (548 sensor tactile glove, grasping 26 objects). In addition, we investigated which dimension wavelet transform-1D, 2D, or 3D-would best compress these tactile interactions. Our results show that wavelet transforms are highly efficient at compressing tactile data and can lead to very sparse and compact tactile representations. Additionally, our results show that 1D transforms achieve the sparsest representations, followed by 3D, and lastly 2D. Overall, the best wavelet for coarse approximation is Symlets 4 evaluated temporally which can sparsify to 0.5% sparsity and compress 10-bit tactile data to an average of 0.04 bits per pixel. Future studies can leverage the results of this paper to assist in the compressive sampling of large tactile arrays and free up computational resources for real-time processing on computationally constrained mobile platforms like neuroprosthetics.
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  • 文章类型: Journal Article
    基于机电致动器的压缩系统需要对其动力学有很好的理解以获得更好的性能。本文研究了具有两个旋转臂的机电系统的非线性动力学,该系统受到正弦激励以进行流体压缩。提出了将两个气球交替压缩的物理模型,并建立了对其动力学进行转换的数学方程。我们强调一些控制参数的影响,即电源电压,不连续位置和粘弹性比对臂角位移行为的影响。该研究还通过忽略系统电气部分中的电感来完成。可以得出,尽管手臂在规则运动期间表现出周期性运动,气球的压缩会导致向多周期或混沌动力学的转变,偶尔恢复到周期性。实验结果与数值模拟结果吻合良好,R系统比RL系统更接近实验结果。这些发现对利用泵技术的各种环境应用具有重要意义。
    Compression systems based electromechanical actuators require a good understanding of their dynamics for a better performance. This paper deals with the study of the nonlinear dynamics of an electromechanical system with two rotating arms subjected to a sinusoidal excitation for fluid compression purposes. The physical model integrating two balloons to be compressed by the arms alternately is presented and the mathematical equations traducing their dynamics are established. We emphasize on the influence of some control parameters namely the supply voltage, the discontinuity position and the viscoelastic ratio on the behaviour of the angular displacement of the arms. The study is also done by neglecting the inductance in the electrical part of the system. It is obtained that while the arms exhibit periodic motion during regular movement, compression of the balloons induces a shift to multi-periodic or chaotic dynamics, occasionally reverting to periodicity. Experimental and numerical simulation results demonstrate good agreement, with the R-system approximating more experimental outcomes than the RL-system. These findings hold significant implications for various environmental applications utilizing pump technology.
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  • 文章类型: Case Reports
    残余的血管移植物可能由于邻近神经结构的压缩而导致显著的神经功能缺损。我们在体外膜氧合拔管和上肢动静脉瘘去除后的两种情况下报告了这一发现。在这两种情况下,去除移植物,补片动脉切开术,和外部神经溶解导致神经功能显着恢复。我们回顾术前检查,诊断研究,和治疗的技术方法,以提高血管和心血管外科医生的认可度,并通过多学科方法证明安全有效的管理选择。
    Remnant vascular grafts may result in significant neurological deficits owing to compression of adjacent neural structures. We report this finding in two cases after extracorporeal membrane oxygenation decannulation and removal of an arteriovenous fistula in the upper extremity. In both cases, removal of the graft, patch arteriotomy, and external neurolysis resulted in significant recovery of neurological function. We review the preoperative workup, diagnostic studies, and technical approach to treatment in an effort to increase recognition among vascular and cardiovascular surgeons and to demonstrate a safe and effective management option through a multidisciplinary approach.
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  • 文章类型: Case Reports
    Guyon管的尺骨神经压迫并不是一个常见的实体,血管病变很少作为该综合征的病原体而涉及。
    方法:我们报告了一例年轻男性患者,因尺动脉动脉瘤导致的Guyon管综合征入院,并接受了手术减压。术后过程顺利,患者对结果感到满意。
    Guyon管综合征涉及许多病因,这些病因可以分组。以前的治疗尝试,症状的持续时间和严重程度以及潜在的病因决定了治疗方案。邻近的血管增大不是Guyon管受压的常见原因,文献中报道了一些病例。在大多数报道中,通过打开和释放Guyon管的顶部并切除动脉瘤的手术治疗有助于取得良好的疗效。
    结论:Guyon管综合征的频率低于肘管综合征或腕管综合征,并且已经描述了许多病原体。血管病变不是压迫腕部尺神经的常见原因,通过这种情况,我们将其视为另一种可能的病因,需要适当的治疗才能获得更好的结果。
    UNASSIGNED: The ulnar\'s nerve compression at the Guyon\'s canal is not a frequent entity add to it that vascular lesions are rarely involved as a causative agent of this syndrome.
    METHODS: We report a case of a young male patient admitted in our department for a Guyon\'s canal syndrome due to an aneurysm of the ulnar artery and underwent a surgical decompression. Post-operative course was uneventful and the patient was satisfied with the result.
    UNASSIGNED: Many etiologies are involved in the Guyon\'s canal syndrome and these etiologies can be arranged into groups. Previous treatment attempts, the duration and severity of the symptoms and the underlying etiology dictate the treatment options. Adjacent vascular enlargement is not a usual cause of Guyon\'s canal compression and a few case reports were reported in the literature. Surgical treatment by opening and releasing the roof of Guyon\'s canal and removing the aneurysm helped to achieve good outcome in most reports.
    CONCLUSIONS: Guyon\'s canal syndrome is less frequent than both cubital tunnel syndrome or carpal tunnel syndrome and many causative agents have been described. Vascular lesions are not the usual cause of compressing the ulnar nerve at the wrist and through this case we spotlighted this entity as another possible etiology requiring an adequate treatment for a better outcome.
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  • 文章类型: Case Reports
    遗传性神经病伴责任压力性麻痹(HNPP)通常由压迫引起,无痛,复发性遗传性神经病,局灶性运动和感觉受累。它始于青春期和成年期。HNPP中最常见的受影响的神经是尺骨,腓骨,径向,正中神经.在这篇文章中,我们介绍了一名31岁的女性患者,患有先前未描述的HNPP病例,在瑜伽的乌鸦位置后,由于the神经被困在螺旋槽中,因此出现了手腕下垂。
    Hereditary neuropathy with liability pressure palsies (HNPP) is usually caused by compression and is an episodic, painless, recurrent hereditary neuropathy with focal motor and sensory involvement. It begins in adolescence and young adulthood. The most commonly affected nerves in HNPP are the ulnar, peroneal, radial, and median nerves. In this article, we present a 31-year-old female patient with a previously undescribed case of HNPP, which presented with wrist drop due to the trapping of the radial nerve in the spiral groove after the crow position in yoga.
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