Design method of an innovative motor for an intra-aortic ventricular assist device

A permanent-magnet motor has been designed for an innovative axial-flow ventricular assist device (VAD), to be placed in the descending aorta, intended to offload the left ventricle and augment renal perfusion in patients with congestive heart failure (CHF). For this application, an intra-aortic impeller with a built-in permanent magnet rotor is driven by an extraaortic stator working in synchronism with the natural heart. To meet this need, a two-dimensional analytical model has been developed in the MATLAB environment to estimate machine parameters; finite element analysis (FEA) has been used to refine the results. A prototype blood pump equipped with an innovative motor designed from the procedure above has been tested in a mock loop representing the human circulatory system. The performance of VAD incorporating the motor is presented. © 2009 IEEE.

Increasing the design strength of glass – fractography and stress testing

Brittleness is the unintended, but inevitable consequence of producing a transparent ceramic for architectural applications such as the soda-lime glass. Its tensile strength is particularly sensitive to surface imperfections, such as that from natural weathering and malicious damage. Although a significant amount of testing of new glass has been carried out, there has been surprisingly little testing on weathered glass. Due to the variable nature of the causes of surface damage, the lack of data on weathered glass leads to a considerable degree of uncertainty in the long-term strength of exposed glass. This paper presents the results of recent tests on weathered annealed glass which has been exposed to natural weathering for more than 20 years. The tests include experimental investigations using the co-axial ring setup as well as optical and atomic force microscopy of the glass surfaces. The experimental data from these tests is subsequently used to extend existing fracture mechanics-based models to predict the strength of weathered glass. It is shown that using an automated approach based directly on finite element analysis results can give an increase in effective design strength in the order of 70 to 100% when compared to maximum stress methods. It is also shown that by combining microscopy and strength test results, it is possible to quantitatively characterise the damage on glass surfaces.

Biofluid behaviour in 3D microchannel systems: Numerical analysis and design development of 3D microchannel biochip separators

This paper describes the design and development cycle of a 3D biochip separator and the modelling analysis of flow behaviour in the biochip microchannel features. The focus is on identifying the difference between 2D and 3D implementations as well as developing basic forms of 3D microfluidic separators. Five variants, based around the device are proposed and analysed. These include three variations of the branch channels (circular, rectangular, disc) and two variations of the main channel (solid and concentric). Ignoring the initial transient behaviour and assuming steady state flow has been established, the efficiencies of the flow between the main and side channels for the different designs are analysed and compared with regard to relevant biomicrofluidic laws or effects (bifurcation law, Fahraeus effect, cell-free phenomenon, bending channel effect and laminar flow behaviour). The modelling results identify flow features in microchannels, a constriction and bifurcations and show detailed differences in flow fields between the various designs. The manufacturing process using injection moulding for the initial base case design is also presented and discussed. The work reported here is supported as part of the UK funded 3D-MINTEGRATION project. © 2010 IEEE.

Design consideration of a circular type magnetic flux pump device

As a variation of the thermally actuated flux pump and the linear type magnetic flux pump (LTMFP), the circular type magnetic flux pump (CTMFP) device is proposed to magnetize a circular shape type-II superconducting thin film and bulk. The basic concept is the same as the thermally actuated flux pump: a circularly symmetric traveling magnetic field is generated below a circular shape superconductor to increase its trapping field. However, this traveling field is created by the three phase windings instead of heating gadolinium block. Apart from the LTMFP, the three phase windings are wound concentrically instead of linearly. The speed of the traveling field is controlled by the AC frequency and the magnitude of the field is controlled by the magnitudes of AC currents. In addition, a coil with DC current is wound around the three phase windings to provide a background field. The concept design is presented in this paper. The magnetic waveforms are analysed numerically by the COMSOL 3.5a software. The impedances of the three phase windings are calculated and a corresponding circuit design is presented. This rig can be used as an advanced tool to study the flux pump behavior of a circular shape superconductor. © 2002-2011 IEEE.

Design methodology of HTS bulk machine for direct-driven wind generation

This paper introduces the design methodology of HTS bulk generator for direct-driven wind turbine. The trap field capability of HTS bulks offer the potential of maintaining similar or even higher magnetic loading level without the iron circuit in the generator. This so-called air-cored design can reduce the weight and increase the power outing per volume of the machine. The detailed design method of the air-cored HTS bulk machine is presented; 3D modeling is applied to consider the total trapped field of bulk arrays; a case study is performed to demonstrate the advantages of air-cored HTS bulk machine over conventional permanent magnet machine. Our results show that the air-cored HTS bulk machine has the potential to maintain the same magnetic loading level as that of the conventional permanent magnet machine. More importantly, it can reduce the total machine weight by 30%. © 2002-2011 IEEE.

Electromagnetic-thermal design optimization of the brushless doubly fed induction generator

In view of its special features, the brushless doubly fed induction generator (BDFIG) shows high potentials to be employed as a variable-speed drive or wind generator. However, the machine suffers from low efficiency and power factor and also high level of noise and vibration due to spatial harmonics. These harmonics arise mainly from rotor winding configuration, slotting effects, and saturation. In this paper, analytical equations are derived for spatial harmonics and their effects on leakage flux, additional loss, noise, and vibration. Using the derived equations and an electromagnetic-thermal model, a simple design procedure is presented, while the design variables are selected based on sensitivity analyses. A multiobjective optimization method using an imperialist competitive algorithm as the solver is established to maximize efficiency, power factor, and power-to-weight ratio, as well as to reduce rotor spatial harmonic distortion and voltage regulation simultaneously. Several constraints on dimensions, magnetic flux densities, temperatures, vibration level, and converter voltage and rating are imposed to ensure feasibility of the designed machine. The results show a significant improvement in the objective function. Finally, the analytical results of the optimized structure are validated using finite-element method and are compared to the experimental results of the D180 frame size prototype BDFIG. © 1982-2012 IEEE.

A novel modeling approach for design studies of brushless doubly fed induction generator based on magnetic equivalent circuit

Brushless doubly fed induction generator (BDFIG) has substantial benefits, which make it an attractive alternative as a wind turbine generator. However, it suffers from lower efficiency and larger dimensions in comparison to DFIG. Hence, optimizing the BDFIG structure is necessary for enhancing its situation commercially. In previous studies, a simple model has been used in BDFIG design procedure that is insufficiently accurate. Furthermore, magnetic saturation and iron loss are not considered because of difficulties in determination of flux density distributions. The aim of this paper is to establish an accurate yet computationally fast model suitable for BDFIG design studies. The proposed approach combines three equivalent circuits including electric, magnetic and thermal models. Utilizing electric equivalent circuit makes it possible to apply static form of magnetic equivalent circuit, because the elapsed time to reach steady-state results in the dynamic form is too long for using in population-based design studies. The operating characteristics, which are necessary for evaluating the objective function and constraints values of the optimization problem, can be calculated using the presented approach considering iron loss, saturation, and geometrical details. The simulation results of a D-180 prototype BDFIG are compared with measured data in order to validate the developed model. © 1986-2012 IEEE.

The design algorithm of an associative memory neural network

A design algorithm of an associative memory neural network is proposed. The benefit of this design algorithm is to make the designed associative memory model can implement the hoped situation. On the one hand, the designed model has realized the nonlinear association of infinite value pattern from n dimension space to m dimension space. The result has improved the ones of some old associative memory neural network. On the other hand, the memory samples are in the centers of the fault-tolerant. In average significance the radius of the memory sample fault-tolerant field is maximum.

Design Study of a Heavily Loaded Ice Class Propeller Using an Advance Panel Method

A design and optimization procedure developed and used for a propeller installed on a twin-semitunnel-hull ship navigating in very shallow and icy water under heavy load conditions is presented. The base propeller for this vessel was first determined using classic design routines under open-water condition with existing model test data. In the optimization process, a panel method code (PROPELLA) was used to vary the pitch values and distributions and take into account the inflow wake distribution, tunnel gap, and cavitation effects. The optimized propeller was able to improve a ship speed of 0.02 knots higher than the desired speed and 0.06 knots higher than the classic B-series propeller. The analysis of the effect of inflow wake, hull tunnel, cavitation, and blade rake angle on propulsive performance is the focus of this paper.

Design optimization of the APF DTL in the SSC-linac

A linear accelerator as a new injector for the SSC (Separated Sector Cyclotron) of the HIRFL (Heavy ton Research Facility Lanzhou) is being designed. The DTL (Drift-Tube-Linac) has been designed to accelerate U-238(34+) from 0.140 MeV/u to 0.97 MeV/u. To the first accelerating tank which accelerates U-238(34+) to 0.54 MeV/u, the approach of Alternating-Phase-Focusing (APF) is applied. The phase array is obtained by coupling optimization software Dakota and beam optics code LINREV. With the hybrid of Multi-objective Genetic Algorithm (MOGA) and a pattern search method, an optimum array of asynchronous phases is determined. The final growth, both transversely and longitudinally, can meet the design requirements. In this paper, the deign optimization of the APF DTL is presented.

A reconsideration of the theological conception of sin in the light of the psychoanalytic conceptions of shame and guilt

Boston University Graduate School of Arts and Sciences. Department of Religion.

Peace and Peacemaking in Paul Against the Backdrop of Greco-Roman Conceptions of Peace

Peace in the ancient world has been studied primarily from the perspective of pacifism and questions related to war and peace. This study employs a socio-historical method to determine how peace was understood in itself, not just with respect to war. It demonstrates that the Greco-Roman world viewed peace as brief periods of tranquility in an existence where conflict was the norm, while Paul regarded peace as the norm and conflict as an intrusive aberration. Through a historical and literary survey of Greco-Roman thought and culture, this study shows that myth, legend, religion, education, philosophy, and science created and perpetuated the idea that conflict was necessary for existence. Wars were fought to attain peace, which meant periods of calm, quiet, and security with respect to the gods, one's inner self, nature, others who are insiders, and others who are outsiders. Despite the desirability of peace, genuine peace was seldom experienced, and even then, only briefly, as underlying enmity persisted without resolution. While Paul supports the prevailing conception of peace as tranquility and felicity in relation to God, self, nature, and others, he differs as to the origin, attainment, and maintenance of peace. In Paul, peace originates in God and is graciously given to those who are justified and reconciled to God through Jesus Christ. God removes the enmity caused by sin and provides the indwelling Spirit to empower believers to think and behave in ways that promote and maintain peace. This study also examines how three social dynamics (honor-shame, patron-client, friendship-enmity) affect Paul's approach to conflict resolution with Philemon and Onesimus, Euodia and Syntyche, believers who are prosecuting one another in civil courts, and Peter. Rather than giving specific procedures for resolving conflict, Paul reinforces the believer's new identity in Christ and the implications of God's grace, love, and peace upon their thoughts, words, and behavior toward one another. Paul uses these three social dynamics to encourage believers in the right direction, but their ultimate accountability is to God. The study concludes with four strategic principles for educating the church and developing an atmosphere and attitude within the church for peacemaking.