课程文献中心 更多>>

关键词： energy systems analysis   ORC   regenerative ORC   thermodynamic   power plants   energy conversion   exergy analysis   waste heat recovery   technologies energy resource recovery   working fluid  

摘要： Organic Rankine Cycle (ORC) is a promising solution for reducing the environmental impact of electricity production. It operates with waste heat from industrial processes and uses low and medium-temperature heat sources. The originality of this work lies not only in conducting an energy analysis of basic and regenerative ORC but also in performing exergy analysis to identify the processes responsible for exergy destruction and losses. It also compares both configurations regarding energy efficiency, exergy efficiency, network, heat required, and exergy destruction rate. Matlab Software runs the simulation using the Coolprop open-source library. These parametric investigations and thermodynamic modelings were undertaken on six working fluids (R113, R134a, R600, R290, R1234yf, and HFE-143 m). Results show a maximum improvement of 17.8% in thermal efficiency and 17.6% in exergy efficiency when transitioning from the basic to the regenerative configuration. Furthermore, the regenerative configuration has about 43% less exergy destruction compared to the basic configuration.

关键词： MATLAB  

摘要： This article proposes a systematic methodology for determining the feasible workspace and deriving critical design parameters of a flexible endoscopic surgical stapler developed for laparoscopic rectal procedures. Pre-operative MRI data from 77 patients (47 male, 30 female from Nantes Hospital), encompassing a diverse range of anatomical variations, were utilized to generate a detailed three-dimensional model of the feasible surgical workspace through manual segmentation of distinct tissue at each MRI layer for each patient. A two-stage optimization process was conducted, beginning with two-dimensional workspace analysis using contouring, binary masking & Euclidean distance transformations and subsequently extending to three-dimensional optimization using MATLAB's fmincon function, to establish a geometrically valid workspace. The optimized workspace facilitated the derivation of design specifications, including the tool's length, and enabled a comparative usability analysis across the patient group. The results indicate that the proposed stapler design is well-suited for use in anatomically constrained environments where conventional tools are inadequate. This approach offers a robust framework for improving the design of robotic surgical instruments, with the potential to enhance precision, adaptability, and clinical outcomes in minimally invasive surgery. © 2025

关键词： MATLAB  

摘要： In electromagnetism, a magnetic dipole is a tiny loop of electric current or a pair of magnetic poles. As the loop size decreases to zero while maintaining a constant magnetic moment, it forms a magnetic dipole. Composed by the magnetic particles, ferromagnetic fluids align with magnetic fields and when a magnetic dipole interacts with such fluids, the particles magnetize the fluid and influence the dipole's field. Hence, this study investigates the magnetic dipole and velocity slip on ternary hybrid ferrofluid flow past a shrinking surface. The model considers three magnetic nanoparticles – iron oxide (Fe3O4), cobalt ferrite (CoFe2O4), and copper (Cu) – dispersed in a base fluid. The similarity transformation technique is applied to derive mathematical models, which were solved numerically using bvp4c program in MATLAB. The analysis reveals that ferrohydrodynamic interaction reduces the skin friction coefficient and heat transfer rate but enhances velocity and temperature profiles. Additionally, the ternary hybrid ferrofluid is also shown to outperform both conventional ferrofluid and hybrid ferrofluid in fluid flow characteristics. Response Surface Methodology (RSM) is employed to identify the optimal combination of parameters, suggesting that the highest ferrohydrodynamic parameter and viscous dissipation, along with minimal Cu-nanoparticle concentration, maximize the heat transfer rate. Contour and surface plots illustrate these optimal conditions. This study highlights an innovative application of ternary ferrofluid with a magnetic dipole and employs RSM to optimize parameters for enhanced heat transfer performance, addressing a gap in existing literature and providing the way for further advancements in this field. © 2025 Elsevier Ltd

关键词： 溶豆   辅食标准   真空冷冻干燥   加速试验   稳定性  

摘要： 为探讨辅食溶豆性质及加速试验期间营养素的衰减,以乳粉、乳清蛋白粉、营养素为主要原料,淀粉、单,双甘油脂肪酸酯、果胶、海藻糖等为辅料,通过冷冻真空干燥、充氮包装等制作了辅食溶豆,并研究了其性质(硬度、脆度、比重和复水时间与市售产品对比)和在加速试验状态下,产品中营养素的稳定性情况.结果表明:辅食溶豆性质与市售竞品接近;在温度(37±2)℃、相对湿度RH为75.00%±5.00%、避免光线直射条件下,6个月内辅食溶豆中营养素均有一定程度的衰减,但营养素含量均在标准范围内.这预测了辅食溶豆货架期的营养素变化规律,为其产品研发提供了有用的参考.

关键词： 煤炭建设工程   质量监督   质量控制   可持续发展  

摘要： 本文聚焦于煤炭建设工程质量监督领域,深入探讨其在煤炭工业发展中的关键作用。从质量监督的基础理论出发,阐述了煤炭建设工程质量监督的目标、原则与方法。详细分析了质量监督在煤炭建设工程各阶段的具体工作内容,包括前期规划、施工过程以及竣工验收阶段。同时,对质量监督过程中面临的复杂地质条件、新技术应用挑战、多主体协调难题等进行了剖析,并提出了相应的解决策略。通过实际案例分析,展示了质量监督措施在煤炭建设工程中的实际成效。此外,还探讨了质量监督人员专业素养提升的重要性与途径,以及煤炭建设工程质量监督的未来发展趋势,包括信息化与智能化、绿色环保理念融入、国际化视野拓展等方面。

关键词： 混沌双机互联电力系统   混合脉冲控制   有限时间稳定性   输入-状态-稳定性  

摘要： 针对混沌电力系统可能导致相角发散、电压崩溃,严重的甚至导致停电等问题,提出了一种基于混合脉冲控制的混沌双机互联电力系统有限时间稳定控制策略。在混沌双机互联电力系统中,给出其有限时间稳定的混合脉冲控制设计,用混合脉冲控制能使其在有限时间内进入稳定运行状态。最后,通过仿真实验验证了所用方法及所提控制策略的有效性与正确性。

关键词： 马铃薯种植   机械化   播种技术   技术要点  

摘要： 马铃薯不仅营养丰富,而且环境适应性强、亩产高、用途广泛,所以在国内诸多地区均有广泛种植,对于保障国家粮食安全、带动食品加工行业发展起着重要作用。文章以甘肃省清水县马铃薯机械化播种技术应用为对象,对马铃薯生产过程各个环节的关键技术进行分析,对机械化播种作业要点进行探讨,为马铃薯种植人员提供参考。

关键词： 直剪方式   FLAC3 D   稳定性   边坡   崩岗  

摘要： [目的]探究不同直剪方式对崩岗土体抗剪性能及边坡稳定性的差异化影响,旨在为边坡治理提供科学依据。[方法]采用不同直剪试验测量抗剪强度参数,并利用FLAC3D软件模拟各剪切条件下边坡稳定性变化,以综合分析不同直剪方式的力学效应。[结果](1)慢剪条件下剪应力响应最大:红土层在荷载400 kPa下慢剪试验中剪应力激增至197.9 kPa,表明其在慢速剪切下具有高强度增长潜力。(2)剪切强度与剪切方式的敏感性:红土层相比过渡层对剪切方式更为敏感,荷载为400 kPa慢剪下的抗剪强度达到194.547 kPa,高于过渡层的182.37 kPa。固结快剪对土体内部力学属性(如内摩擦角和黏聚力)的改变最为明显。(3)边坡稳定性分析:慢剪不仅安全系数低(FS=3.18),且伴随较大剪应变增量及广泛变形区域,明确其为最不稳定剪切模式。崩岗边坡X轴应力均朝向坡面,最大约为22 kPa,所有剪切方式下位移均初增后减,但固结快剪位移量及方向有别于其他试验,显示位移量较大,方向朝向坡外。Y轴应力随深度增加递减,慢剪下剪应力变幅尤为突出。[结论]在不同的直接剪切方式作用下,抗剪强度的绝对差异虽不显著,但内摩擦角与黏聚力相差较大。经数值模拟分析可知,慢剪条件对崩岗边坡的稳定性构成了最大的挑战。

关键词： 生姜   丰产技术   栽培技术   田间管理  

摘要： 生姜用途广泛,在全球范围内有着广泛的种植和消费需求。生姜栽培过程中会受到多种因素的影响,导致产品质量和产量不稳定。分析生姜丰产栽培技术及其田间管理要点,旨在提高生姜的产量和品质。同时通过病虫害治理等措施,实现生姜的优质高产,在降低生产成本的同时,提高种植者的经济效益。

关键词： 双侧缺陷   慢性踝关节不稳   踝关节扭伤   感觉运动   平衡控制   本体感觉   足底皮肤触觉   工程化组织构建  

摘要： 背景:单侧慢性踝关节不稳会对患侧肢体产生不良影响,有线索表明非患侧可能同样受到累及,但目前尚缺乏直接证据。目的:探讨单侧慢性踝关节不稳对于双侧姿势稳定性、本体感觉、足底触觉和肌肉力量的影响。方法:招募122例受试者,其中单侧慢性踝关节不稳者67例,非慢性踝关节不稳者55例。测试了单侧慢性踝关节不稳者双侧以及非慢性踝关节不稳者的姿势稳定性、本体感觉、足底触觉和肌肉力量。使用单因素方差分析或克鲁斯卡尔-沃利斯检验对比组间差异。结果与结论:①相较于非慢性踝关节不稳者,单侧慢性踝关节不稳者双侧前后方向的稳定时间均更长(P=0.001-0.012),患侧内外方向的稳定时间更长(P=0.012-0.025);双侧踝关节跖屈、背伸、内翻和外翻的本体感觉阈值均更高(P=0.000-0.035);双侧足底大脚趾、第1跖骨头、第5跖骨头、外侧足弓、足跟的足底触觉灵敏度均更低(P=0.000-0.008);双侧踝关节内翻和外翻的肌肉力量均更弱(P=0.000-0.019)。②单侧慢性踝关节不稳者存在双侧姿势稳定性、本体感觉、足底触觉和肌肉力量缺陷。因此,在治疗慢性踝关节不稳时应全面考虑双侧肢体的康复需求。