Numerical simulations of the infusion of adriamycin using a physiological flow model

The antineoplastic drug Adriamycin is administered by short term i.v. infusion. The drug is noted for its acute and chronic cardiotoxicity in addition to its toxicity on the bone marrow and gut. A physiological flow model and computer program, which contains a subprogram for continuous infusion of a drug, was used to simulate the distribution of Adriamycin during infusion in heart, bone marrow, gut, kidney, muscle, skin, liver adn bile. Simulations were carried out for 1, 2, 5, 10 and 20 min of infusion. Computations were made for the concentration of drug in these organs as a function of time over a total period of 48 min. Simulations showed the heart and kidney would contain high concentrations of drug during infusion which rapidly declined upon cessation of infusion. Bone marrow and gut showed a less rapid accumulation and decline. Muscle and skin showed even a slower accumulation and decline. Simulations also showed the effect of altering the rate of infusion on the concentration in the liver and excretion in the bile.     

Computer-assisted analysis of the vascular endothelial cell motile response to injury

We have developed an automated, user-friendly method to track vascular endothelial cell migration in vitro using an IBM PC/XT with MS DOS. Analog phase-contrast images of the bovine aortic endothelial cells are converted into digital images (8 bit, 250 x 240 pixel resolution) using a Tecmar Video VanGogh A/D board. Digitized images are stored at selected time points following mechanical injury in vitro. FORTRAN and assembly language subroutines have been implemented to automatically detect the wound edge and the edge of each cell nucleus in the phase-contrast, light-microscope field. Detection of the wound edge is accomplished by intensity thresholding following noise reduction in the image and subsequent sampling of the wound. After the range of wound intensities is determined, the entire image is sampled and a histogram of intensities is formed. The histogram peak corresponding to the wound intensities is subtracted, leaving a histogram peak that gives the range of intensities corresponding to the cell nuclei. Rates of cell migration, as well as cellular trajectories and cell surface areas, can be automatically quantitated and analyzed. This inexpensive, automated cell-tracking system should be widely applicable in a variety of cell biologic applications.     

液体流量标准装置中开式换向器测量误差模型研究

针对液体流量标准装置中开式换向器对流量测量带来误差问题,分析了目前开式换向器测量不确定度分析中存在的局限性;在考虑换向挡板位置及喷嘴流速分布实际情况的基础上,建立了换向挡板在换入/换出行程的不同位置时引入的开式换向器流量测量误差模型。采用改变换向挡板位置的方法,并基于新建模型对开式换向器在流量测量中引入的测量误差进行了理论计算,计算结果与试验数据进行了比对,取得了较好的一致性。结果表明,本文建立的换向挡板在换入/换出行程的不同位置时引入的测量误差数学模型是合理的,能够满足开式换向器流量测量误差的分析计算。     

Investigating the differential activation of vascular endothelial growth factor (VEGF) receptors

The vascular endothelial growth factors are key mediators of angiogenesis and are also related to several physiological processes such as monocyte chemotaxis, dendritic cell development, hematopoietic stem cell survival, and many others. PlGF, VEGF, VEGFB, VEGFC and VEGFD were identified as members of the vascular endothelial growth factor family. They act by differential activation of three receptors: Flt-1, KDR and Flt-4. PlGF and VEGFB only activate Flt-1. VEGF activates both Flt-1 and KDR. VEGFC and VEGFD activate KDR and Flt-4. The available three dimensional structures of VEGF and PlGF, in complex with the domain-2 of Flt-1, show that both proteins bind in a very similar way to Flt-1 receptor. Here we construct the three dimensional model of the domain-2 of KDR receptor using the same domain of Flt-1 as template. We also construct the model complexes VEGF/KDR, VEGFB/Flt-1, VEGFB/KDR and PlGF/KDR. Molecular dynamics simulations with explicit solvent are carried out on eleven molecular systems: unbound VEGF, VEGF/Flt-1_D2, VEGF/KDR_D2, unbound PlGF, PlGF/Flt-1_D2, PlGF/KDR_D2, unbound VEGFB, VEGFB/Flt-1_D2, VEGFB/KDR_D2, unbound Flt-1_D2 and unbound KDR_D2. We analyze protein–protein interactions, shape complementarity, charge complementarity and hydrogen bonds. As a coarse estimation of the desolvation penalties, we assume a correlation to the number of hydrogen bonds with solvent molecules that are lost upon complex formation. The results herein are consistent with the experimental selectivity profile (VEGF being able to activate both Flt-1 and KDR receptors while VEGFB and PlGF being only able to activate Flt-1), and provide a collection of evidences sustaining the complementarity of polar interactions as the main responsible for protein recognition and selectivity.     

A finite element model of fluid flow in the vocal tract

A finite element model of the vocal tract was made in which the time-dependent, compressible, Navier Stokes equations were solved. No assumptions or simplifications in the physics were made, but a simple fixed wall tube was used as the vocal tract wall. The model was used to study the various effects that may be observed which are due to the Navier Stokes equations' non-linear and stress-related terms. These terms contribute boundary layer effects and energy transfers between frequency bands. Overall, the finite element model proved capable of resolving many effects that are not explained by linear theory. Two set of experiments were performed on the model to examine both time-varying and steady-state responses. Using the model a complete synthetic dipthong was produced to demonstrate the use of the system. The boundary layers could be distinguished, and their effect on the overall response demonstrated.     

Hypertext model of electronic document flow

Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 178–185, March–April, 1995.     

Numerical simulation of the flow field in a model of the nasal cavity

Results of a numerical simulation of the flow in a model of the human nasal cavity using an AUSM-based method of second-order accuracy on a multi-block structured grid are presented and compared with experimental data. Computations are performed for inspiration and expiration at rest with Reynolds numbers Re=1560 and Re=1230 at the nostril, respectively. The comparison shows good agreement with experimental findings.     

A hierarchical model for structure learning based on the physiological characteristics of neurons

Almost all applications of Artificial Neural Networks (ANNs) depend mainly on their memory ability. The characteristics of typical ANN models are fixed connections, with evolved weights, globalized representations, and globalized optimizations, all based on a mathematical approach. This makes those models to be deficient in robustness, efficiency of learning, capacity, anti-jamming between training sets, and correlativity of samples, etc. In this paper, we attempt to address these problems by adopting the characteristics of biological neurons in morphology and signal processing. A hierarchical neural network was designed and realized to implement structure learning and representations based on connected structures. The basic characteristics of this model are localized and random connections, field limitations of neuron fan-in and fan-out, dynamic behavior of neurons, and samples represented through different sub-circuits of neurons specialized into different response patterns. At the end of this paper, some important aspects of error correction, capacity, learning efficiency, and soundness of structural representation are analyzed theoretically. This paper has demonstrated the feasibility and advantages of structure learning and representation. This model can serve as a fundamental element of cognitive systems such as perception and associative memory.     

A framework for physiological indicators of flow in VR games: construction and preliminary evaluation

Flow experience is often considered as an important standard of ideal user experience (UX). Till now, flow is mainly measured via self-report questionnaires, which cannot evaluate flow immediately and objectively. In this paper, we constructed a physiological evaluation model to evaluate flow in virtual reality (VR) game. The evaluation model consists of five first-level indicators and their respective second-level indicators. Then, we conducted an empirical experiment to test the effectiveness of partial indicators to predict flow experience. Most results supported the model and revealed that heart rate, interbeat interval, heart rate variability (HRV), low-frequency HRV (LF-HRV), high-frequency HRV (HF-HRV), and respiratory rate are all effective indicators in predicting flow experience. Further research should be conducted to improve the evaluation model and conclude practical implications in UX and VR game design.     

Simulations of transonic shock-tube flow with a model micro-cylinder in the driver

A unique hand-held needle-free powder injection system, using a transient shock-tube flow to deliver powder genes and drugs into human skin for a wide range of treatments, has been proposed. In the development of such devices, a strong non-linear phenomenon, possibly shock process instead of unsteady expansion waves, was observed in the driver portion of the shock-tube flow in the presence of a gas micro-cylinder. In this paper, we further investigate effects of a model micro-cylinder in the driver on the gas dynamics of a prototype clinical device numerically. To accurately simulate such complex shock-tube flows, an efficient numerical solver, MIFVS, is extended to incorporate with a transition-modified turbulence model. Comparison with experimental measurements shows that the extended MIFVS accurately predicts pressure traces in both laminar and turbulent regimes. The separation zone due to a strong non-linear process is properly captured via such transition-modified turbulence model. Numerical investigations and discoveries are presented and discussed.     

志愿者计算模型在电力系统潮流计算中的运用

提出了一种电力系统潮流计算并行处理的新方法,该方法使用基于协同服务器组的志愿者计算平台P2HP作为高性能编程环境和运行平台。分析了大规模电力系统潮流计算问题在P2HP计算平台上的任务划分、并行粒度和实现技术。使用对象序列化技术和本地接口调用技术可以使潮流计算应用程序跨平台运行。仿真计算结果证明,这种方法能够满足安全性、实时性要求很高的大规模潮流计算应用的需求,具有较好的加速比和运行效率。     

Multi-commodity flow network model of the flight gate assignment problem

The flight gate assignment problem is encountered by gate managers at an airport on a periodic basis. This assignment should be made so as to balance carrier efficiency and passenger comfort, while providing buffers for unexpected events that cause assignment disruptions. In this paper, a binary integer multi-commodity gate flow network model is presented with the objective of minimizing the fuel burn cost of aircraft taxi by type and expected passenger discomfort for “tight” connections as a function of inter-gate distance and connection time. This approach is shown to be computationally efficient within a decomposition approach for large problem instances. A numerical application of this approach is given for the gating of Continental Airlines at George W. Bush Intercontinental Airport in Houston (IAH).     

Improving the efficiency of a Godunov-based free surface flow model

Models for simulating turbulent, nonhydrostatic, free surface flow are highly complex and require the combination of several different physical phenomena. Consequently, there are many different approaches to design such a model. This paper explores ways to improve the numerical efficiency of an existing free surface flow model without severely sacrificing its accuracy. Specifically, this paper investigates alternative methods for integrating diffusion as well as extending the model to nonhydrostatic flow.     

Multi-commodity flow network model of the flight gate assignment problem

The flight gate assignment problem is encountered by gate managers at an airport on a periodic basis. This assignment should be made so as to balance carrier efficiency and passenger comfort, while providing buffers for unexpected events that cause assignment disruptions. In this paper, a binary integer multi-commodity gate flow network model is presented with the objective of minimizing the fuel burn cost of aircraft taxi by type and expected passenger discomfort for “tight” connections as a function of inter-gate distance and connection time. This approach is shown to be computationally efficient within a decomposition approach for large problem instances. A numerical application of this approach is given for the gating of Continental Airlines at George W. Bush Intercontinental Airport in Houston (IAH).     

A two-dimensional,second-order model for turbulent flow in the upper atmosphere

A second order closure model for the atmospheric, two-dimensional, steady, turbulent flow in a zonal channel for the β-plane is developed, and the non-linear system of equations resulting from the model is solved using a standard iterative technique. An important feature of the model is that it attempts to simulate thermal effects in the energy- and enstrophy budgets by introducing a fictitious buoyancy-like forcing term, which corresponds to a baroclinic force field of intensity Γ[T] acting southwards in the β-plane. From the original governing equations a full set of relations for the Reynolds stresses is developed, in addition to one equation each for the mean momentum- and the energy balance (in the energy equation, a Boussinesq approximation is employed). The governing equations are properly scaled from synoptic observations to closely resemble those of the large eddy dynamics, Then, an invariant modelling technique is used, to obtain a non-linear system for the Reynolds'- and the thermal stresses. Since the source of energy required to maintain the flow is in the mean temperature difference between two limiting latitude circles, the [negative] temperature gradient is assumed from empirical data corresponding to a stable environment. The model parameters are reduced to standard Reynolds-, Rossby-, Richardson- and Prandtl numbers. A two-step double iterative procedure is employed to achieve convergence while maintaining physically sound profiles. The model shows a very high sensitivity to the turbulent kinetic energy profile, and the predicted energy conversion mechanisms, in particular the meridional eddy momentum flux, the eddy potential energy, and the temperature variances, are in good agreement with the available experimental data. In particular, the model reproduces reasonably well the general dynamics of synoptic flows, including the reverse energy cascade and the direct enstrophy cascade. Further possible developments and feasible research topics in this area are briefly discussed.     

基于Poisson-Nernst-Planck模型的微通道电渗流数值模拟

采用由电解质溶液离子输运Nernst-Planck方程、流体运动Navier-Stokes方程和电场Possion方程建立的Possion-Nernst-Planck模型,应用有限元分析方法研究二维光滑微通道电渗流输运特性和离子分布。对比分别基于Possion-Nernst-Planck模型和Poisson-Boltzmann模型数值模拟结果,结果表明:Possion-Nernst-Planck模型能更准确地模拟计算微通道中的电渗流输运特性和离子分布。     

Dynamic material flow control in mixed model assembly lines

This study investigates the control of material flow in mixed model assembly lines. It focuses on the use of tugger trains to feed stations in assembly lines by materials and parts from a warehouse or a supermarket. The movement of tugger trains is based on the principle of in-plant milk run. The study considers a strategy to deal with disturbances such as machine breakdown, line stoppage, defective parts, and resequencing of product models. These disturbances lead to unexpected fluctuations in stations demand for parts. The strategy is applied using a mix between the demand-oriented and e-kanban systems to facilitate the planning of three problems, namely, train routing, scheduling, and loading. The information obtained using e-kanban is combined with the information about the expected stations demand based on previously known sequence of product models and the materials needed for each model. Routing was investigated analytically while scheduling and loading problems were investigated using integer programming. Results showed that the method proposed outperforms the traditional methods of material flow planning.     

The message flow model for routing in wormhole-routed networks

In this paper, we introduce a new approach to deadlock-free routing in wormhole-routed networks called the message flow model. This method may be used to develop deterministic, partially-adaptive, and fully-adaptive routing algorithms for wormhole-routed networks with arbitrary topologies. We first establish the necessary and sufficient condition for deadlock free routing, based on the analysis of the message flow on each channel. We then use the model to develop new adaptive routing algorithms for 2D meshes     

A network flow model for load balancing in circuit-switchedmulticomputers

In multicomputers that utilize circuit switching or wormhole routing, communication overhead depends largely on link contention-the variation due to distance between nodes is negligible. This has a major impact on the load balancing problem. In this case there are some nodes with an excess load (sources) and other with a deficit load (sinks). A matching of sources to sinks is required to avoid contention. The problem is made complex by the hardwired routing on currently available machines: The user can control only which nodes communicate but not how the messages are routed. Network flow models of message flow in the mesh and the hypercube have been developed to solve this problem. The crucial property of these models is the correspondence between minimum cost flows and correctly routed messages. To solve a given load balancing problem, a minimum cost flow algorithm is applied to the network. This permits the efficient determination of a maximum contention free matching of sources to sinks that, in turn, tells how much of the given imbalance can be eliminated without contention