Analysis of Three-Dimensional Flow Birefringence Models, with a Note on the Effects of Catheters and Needles on Vessel Flow

Flow birefringence is a convenient and useful technique for studying the initiation and propagation of fluid disturbances in transparent models of the cardiovascular system. Prior quantitative work has been restricted to analysis of two-dimensional systems using shallow channels. The theory of flow birefringence is discussed and a technique for analysis of three-dimensional models is proposed.     

Laser-Machined Shape Memory Alloy Actuators for Active Catheters

Medicine is undergoing a transformation toward minimally invasive surgery, and with it comes an increasing need for more precise miniature instruments to accurately execute complex procedures. In catheter-based surgeries, the physician must control the tip of the catheter from a distal point outside the body, which makes it difficult to achieve precise manipulative control. Providing actuation local to the desired point of manipulation will greatly improve the physician's ability to intervene on diseases in a minimally invasive fashion. We present a new actuator made from laser machining shape memory alloy (SMA) tubes for use in an active steerable catheter. Using finite-element analysis and experimental verification, we have designed a 1.5-mm-long SMA actuator cut from 1.27-mm-diameter NiTi tubing that exhibits good fatigue properties, and can produce forces of 12 N at 20% elongation. We use an iterative rapid design process, so that many actuator geometries can be tested quickly to achieve the desired mechanical properties without complex material models. In this paper, we describe the design and testing of the actuator, and verify its force, elongation, and fatigue properties.     

Petromyzontidae-Biomimetic Multimodal Microneedles-Integrated Bioelectronic Catheters for Theranostic Endoscopic Surgery

Current catheter devices in minimally invasive surgery still possess limited functional options, lacking multimodal integration of both sensing and therapy. Catheter devices usually operate outside the tissue, incapable to detect intra-tissue biochemical information for accurate localization and assessment of lesions during surgery. Inspired by the feature and functions of Petromyzontidae, here a multimodal core-shell microneedles-integrated bioelectronic catheter (MNIBC) for tissue-penetrating theranostics in endoscopic surgery is developed. The microneedle (MN) device possesses individually addressable functionality at single-MN tip resolution, enabling multiplex functions (a total of 11 functions distributed in three types of catheters) including biochemical sensing, myoelectric modulation, electroporation, and drug delivery in a submucosal environment. The MNIBC is prepared through hybrid fabrication and dimensionality reduction strategies, where the MN electrodes are functionalized with an MXene-carbon nanotube (MXene-CNT)-based electron mediator, addressing the challenge of reduced electrode sensitivity on ultra-small MN tip. The functionalities of MNIBC are demonstrated both ex vivo and in vivo on anesthetized rabbits via laparoscopy, simulated cystoscopy, and laparotomy. The MNIBC can effectively detect intra-tissue biochemical signals in the bladder, and offers localized electroporation and intra-tissue drug delivery for precise treatments of lesions. The versatile features of the MNIBC present a highly advanced platform for precise surgeries.     

Thermally Induced Viscous Flow of Borophosphosilicate-Glass Thin Films on Stepped Surfaces,Part 2: Generalized Parameters for ULSI Glass Flow Characterization

New flow parameters termed flow effectiveness andthermal budgetare used for the characterization of the thermal flow of borophosphosilicate glass serving as a premetal dielectric in ULSI circuits. Their practical value is discussed. It is concluded that the approach proposed reduces the cost of measurement, facilitates the interpretation of measured data, works for both furnace and rapid thermal annealing, is applicable to ULSI gap filling as well as glass planarization, and enables one to optimize the annealing temperature for thin films of low-fusible multicomponent glasses.     

不同冲管溶液对预防PICC置管期间血栓性静脉炎的效果研究

目的：探讨肝素稀释液在预防PICC置管期间血栓性静脉炎的效果。方法：选择2006-2009年期间,在我科行PICC置管,排除凝血功能障碍及血液系统疾病的患者128例,随机分为实验组和对照组,实验组64例,在输液前后抽取肝素稀释液（浓度为10u/ml）5ml至10ml行冲管和正压封管,输液间歇期,用同样肝素稀释液5ml至10ml行冲管和正压封管,每周2次。对照组64例只用0.9%NS冲管和正压封管,方法与实验组相同。观察2组病人置管后1个月内发生静脉炎的临床表现、血浆钎维蛋白原（FIB）值的变化,并对有典型临床症状患者分别进行血液D-二聚体值及彩色多普勒超声检查。结果：对照组有明显静脉炎表现者13例,实验组6例,通过血D二聚体值测定和彩色多普勒超声检查显示,对照组13例患者中,9例患者符合血栓性静脉炎诊断标准,4例为非血栓性静脉炎,实验组的6例患者中,均不符合血栓性静脉炎诊断标准,血浆钎维蛋白原（FIB）值的变化,两组患者有显著差异。结论;用低浓度肝素稀释液冲管和封管,对排除凝血功能障碍及血液系统疾病的患者,可有效预防PICC置管期间血栓性静脉炎的发生。     

轴对称流场的计算流动显示算法

讨论了全息干涉、纹影、阴影的计算光学原理 ,对数值计算的结果进行图形处理以模拟光学仪器的工作过程。针对轴对称流场的特殊性 ,对三维的光程积分计算进行简化 ,采用环带法用二维的计算网格计算出三维的沿光线的积分结果 ,发展了一套轴对称流场的计算流动显示的快速算法。通过计算流场图像与试验流场图像的直接比较 ,可以验证数值计算的有效性。示例给出了弹道靶中高超声速钝锥流动的应用     

Power Flow Characterization of a Bidirectional Galvanically Isolated High-Power DC/DC Converter Over a Wide Operating Range

This paper studies the power flow characterization of a bidirectional galvanically isolated high-power dual active bridge dc/dc converter. In experimental tests at the University of Michigan, we have observed three phenomena, which we term as internal power transfer, phase drift, and low system efficiency, that are present under certain operating conditions. These phenomena cannot be explained by conventional power transfer analysis. The authors develop a new model, based on a detailed analysis over a short time scale, that incorporates additional parameters, including the power semiconductor voltage loss and dead time. The new power flow model may be used to explain the observed phenomena and to characterize the power flow of the converter. The model may also be used to perform accurate power flow computations over a wide operating range, thereby supporting optimal hardware design, operating range selection, and power management strategy development. Experimental results are presented to illustrate the validity of the new model.      

Characterization of the Coronary Vascular Capacitance, Resistance, and Flow in Endocardium and Epicardium Based on a Nonlinear Dynamic Analog Model

An electrical analog model consisting of capacitors, diodes, linear, and nonlinear resistors was used to characterize the coronary pressure-flow relationships from the arterial side of the coronary circulation. Based on this analog model, an identifiable system was formulated whereby the coronary vascular capacitance and resistance in the endocardial and epicardial layer of the heart were estimated. This was done by solving a constrained least-squares problem using a nonlinear programming technique. Experimental data were obtained from 28 animal studies using swine with an artificially induced coronary stenosis. The analog model showed a very consistent representation of the coronary hemodynamics. The model also generated accurate estimates of the endocardial to epicardial blood flow ratios compared to those independently measured by the radioactive microsphere technique. The model-predicted epicardial capacitance had a mean of 4.2 ×10-3 mI/mmHg per 100 g tissue; while the endocardial capacitance was negligible in most cases. The result indicated that, in the stenosed coronary circulation of swine, capacitive flow contributes 20 percent in root-mean-square value to the total flow activity in epicardium; while flow in the endocardium is dominated by a resistive, vascular waterfall effect.     

复合流场上吸罩流场理论分析

提出在计算复合流场内存在两种不同流态的流动:势流和紊流。针对两种流动,分别建立了其数学模型,对于紊流流场,针对标准k-ε紊流模型的缺陷,采用了RNGk-ε紊流模型使紊流控制方程封闭。以及提出了边界条件的确定原则。为复合流场的数值计算提供了理论指导。     

仿生毛发气流传感器在流场中的传感特性研究

模仿昆虫感受器的结构,设计制备了一种仿生毛发气流传感器——表面对称电极含金属芯聚偏氟乙烯(PVDF)纤维（SMPF）传感器。基于流体力学理论和第一类压电方程建立了SMPF的气流传感模型。搭建了实验系统,验证了SMPF对于气流速度的传感能力。实验结果表明,SMPF的输出信号和气流速度的平方成线性关系,验证了理论模型,表明SMPF具有感知气流速度的能力。将纤维呈阵列排布置于风洞流场中,用气流对纤维阵列进行冲击,搭建实验系统,验证了纤维在流场中的传感特性,并进行有限元仿真分析。实验结果表明,在风洞装置中,当有气流流过时,会产生流动边界层,且沿着气流速度方向边界层厚度越来越厚,同一截面上的气流速度差也越来越大。实验结果验证了理论模型,表明SMPF具有感知流场分布的能力。     

静脉内弱激光照射血液治疗帕金森氏病

采用静脉内弱激光照射血液疗法（ILIB）治疗32例帕金森氏病患者，总有效率达87．6％。作者推测，ILIB可能通过改善脑微循环，纠正脑内多巴胺代谢紊乱从而防治帕金森氏病。     

自动流量平衡阀过流曲线激光切割工艺

采用Nd:YAG激光器切割自动流量平衡阀过流曲线,以切缝宽度、切口表面粗糙度和熔渣量作为衡量指标,研究输出电流、扫描速度、焦点位置、辅助气体种类和压力对自动流量平衡阀过流曲线切割质量的影响。获得了较为理想的切割工艺参数:输出电流为175 A,脉冲宽度为0.3 ms,脉冲频率为70 Hz,扫描速度为40 mm/s,氧气压力为1.0 MPa,离焦量为0。采用该工艺参数,切割出了高质量的过流曲线。     

EOS技术的流量控制方法

可承载IP业务、视频业务和TDM业务等多种业务的网络平台MSTP的核心技术是实现基于传输网的以太网(Ethernet over SDH,EOS).首先介绍了X.86标准实现以太网帧到SDH传输净荷的映射的原理,详细讨论了EOS技术中流量控制的机制,实现了以太网数据传输速率控制,避免了以太网帧映射到VC4净荷时的数据丢失.     

基于物联网的医院点滴监测管理系统

以STM32芯片作为控制核心,利用物联网、无线传输、MQTT通信协议、JSON数据包格式解析等技术,实现了对医院内静脉输液情况的智能化监控管理。病人、监护人可以通过手机或病房内液晶显示屏交互方式查看自己的输液情况,医护人员可以通过电脑监控医院内所有病床正在进行静脉输液的情况。该设计实现了输液余量实时监测、滴速智能调节以及手动控制、短信提示、药瓶识别播报、一键呼叫护士、输液加热、智能告警等功能。     

Flow control in distributed gateways

The resultant traffic flows in a preferred direction within a set of cooperative gateway nodes is optimized taking into consideration the internal rate-delay products. The internal rates on directed links among adjacent gateway nodes are included in the set of control variables. It is also shown that the optimal internal rate-delay product of a set of connected gateway nodes can be obtained by locally optimizing in each node the rates of either the input ports or the output ports. The effectiveness of the proposed optimization algorithm is demonstrated for a typical sample gateway of three nodes with inhomogeneous arrival and service rates.     

静脉输液报警装置中液位信号的检测原理

为减轻护士的劳动强度、患者家属负担、保证输液安全,文中通过采用光电式、电容式、超声、力学、图像等液位检测方法,设计了一种输液监视报警装置。通过监视物理量的变化,以实时监控液位信息,再将相关信号传送到后续报警电路,从而实现自动报警。实验证明,该设计可以有效实现对药液液位的监测、报警、显示等功能。     

质量流量计流量误差分析

质量流量计（ＭＦＣ）广泛用于微电子工艺气体的流量控制。硅片制造工艺水平通常取决于对工艺过程中气体流量的精确控制。目前在线使用的质量流量计对工艺过程有较大影响包括质量流量计的设计 缺陷和外围条件的影响。现代工艺水平对工艺过程有较大影响。包括流量计的设计缺陷和外围条件的影响。现代工艺水平对质量流量计提出了更高要求，根据质量流量计的设计机理和外围条件，分析了ＭＦＣ对相关气体工艺的影响，质量流量计带来的问     

从手机微博看移动互联网业务的信息流、数据流、承载流

分析了移动互联网新兴的微博业务,研究微博业务特性、业务流程,并通过微博业务的测试分析,了解微博业务的各个交互流程,每个业务流程的流量、流向,并根据测试结果,评估分析微博业务对网络的影响。通过对微博这一典型业务的分析,观察移动互联网时代业务的信息流、数据流、承载流之间的关系,探讨未来移动互联网业务的发展对移动网络可能带来的压力。     

Flow theory

We develop a simple theory of flows to study the flow of data in real-time computing networks. Flow theory is based on discrete and nondeterministic mathematics, rather than the customary continuous or probabilistic mathematics. The theory features two types of flows: smooth and uniform, and eight types of flow operators. We prove that, if the input flow to any of these operators is smooth or uniform, then both the internal buffer and delay of that operator are bounded. Linear networks of flow operators are introduced, and their internal buffers and delays are derived from the internal buffers and delays of their constituent operators. We extend flow theory so that it can be used in analyzing cyclic networks and networks of multiflows. Since many rate-reservation protocols can be represented as linear networks of flow operators, we use flow theory to prove that a number of these protocols (stop-and-go, hierarchical round-robin, weighted fair queueing, self-clocking fair queueing, and virtual clock) require bounded buffering and introduce bounded delay