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Part Series (part + series)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Fuel Cell Vehicle Simulation , Part 1: Benchmarking Available Fuel Cell Vehicle Simulation Tools

FUEL CELLS, Issue 3 2003
K.H. Hauer
Abstract Fuel cell vehicle simulation is one method for systematic and fast investigation of the different vehicle options (fuel choice, hybridization, reformer technologies). However, a sufficient modeling program, capable of modeling the different design options, is not available today. Modern simulation programs should be capable of serving as tools for analysis as well as development. Shortfalls of the existing programs, initially developed for internal combustion engine hybrid vehicles, are: (i)Insufficient modeling of transient characteristics; (ii) Insufficient modeling of the fuel cells system; (iii) Insufficient modeling of advanced hybrid systems; (iv) Employment of a non-causal (backwards looking) structure; (v) Significant shortcomings in the area of controls. In the area of analysis, a modeling tool for fuel cell vehicles needs to address the transient dynamic interaction between the electric drive train and the fuel cell system. Especially for vehicles with slow responding on-board fuel processor, this interaction is very different from the interaction between a battery (as power source) and an electric drive train in an electric vehicle design. Non-transient modeling leads to inaccurate predictions of vehicle performance and fuel consumption. When applied in the area of development, the existing programs do not support the employment of newer techniques, such as rapid prototyping. This is because the program structure merges control algorithms and component models, or different control algorithms (from different components) are lumped together in one single control block and not assigned to individual components as they are in real vehicles. In both cases, the transfer of control algorithms from the model into existing hardware is not possible. This paper is the first part of a three part series and benchmarks the "state of the art" of existing programs. The second paper introduces a new simulation program, which tries to overcome existing barriers. Specifically it explicitly recognizes the dynamic interaction between fuel cell system, drive train and optional additional energy storage. [source]

Pan Evaporation Trends and the Terrestrial Water Balance.

GEOGRAPHY COMPASS (ELECTRONIC), Issue 2 2009

Pan evaporation is just that , it is the evaporation rate of water from a small dish located at the ground-surface. Pan evaporation is a measure of the evaporative demand over terrestrial surfaces. Declines in pan evaporation have now been reported in many regions of the world. The trends vary from one pan to the next, but when averaged over many pans, they are typically in the range of ,1 to ,4 mm a,2 (mm per annum per annum). In energetic terms, a trend of ,2 mm a,2 is equivalent to ,0.16 W m,2 a,1 and over 30 years this is a change of ,4.8 W m,2. For comparison, the top-of-atmosphere forcing due to doubled CO2 is estimated by the Intergovernmental Panel on Climate Change (IPCC) to be ~3.7 W m,2. Hence, the magnitude of the pan evaporation trend is large. What is of even greater interest is the direction , a decline , given the well-established warming of the last 30,50 years. In this article, the first in a two part series, we describe the underlying principles in using and interpreting pan evaporation data and then summarise the reported observations from different countries. In the second article, we describe the interpretation of the trends in terms of changes in the terrestrial water balance. [source]

Comparison of waveform inversion, part 3: amplitude approach

GEOPHYSICAL PROSPECTING, Issue 4 2007
Sukjoon Pyun
ABSTRACT In the second paper of this three part series, we studied the case of conventional and logarithmic phase-only approaches to full-waveform inversion. Here, we concentrate on deriving amplitude-only approaches for both conventional- and logarithmic-based methods. We define two amplitude-only objective functions by simply assuming that the phase of the modelled wavefield is equal to that of the observed wavefield. We do this for both the conventional least-squares approach and the logarithmic approach of Shin and Min. We show that these functions can be optimized using the same reverse-time propagation algorithm of the full conventional methodology. Although the residuals in this case are not really residual wavefields, they can both be considered and utilized in that sense. In contrast to the case for our phase-only algorithms, we show through numerical tests that the conventional amplitude-only inversion is better than the logarithmic method. [source]

Differential diagnosis of T2 hyperintense spinal cord lesions: Part B

JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 2 2009
P Bou-Haidar
Summary Hyperintense spinal cord signal on T2-weighted images is seen in a wide-ranging variety of spinal cord processes. Causes including simple MR artefacts, trauma, primary and secondary tumours, radiation myelitis and diastematomyelia were discussed in Part A. The topics discussed in Part B of this two part series include multiple sclerosis, subacute combined degeneration of the spinal cord, cord infarction, arteriovenous shunts, transverse myelitis, neurosarcoidosis, AIDS-associated vacuolar myelopathy, and syringohydromyelia. Characterization of the abnormal areas of T2 signal as well as their appearance on other MR imaging sequences, when combined with clinical context and laboratory investigations, will often allow a unique diagnosis, or at least aid in narrowing the differential diagnosis. A wide range of instructive cases is discussed here, with review of the published reports focusing on pertinent MR features to aid in diagnosis. [source]

Magnetic resonance imaging of ankle tendons and ligaments: Part I , Anatomy

JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 4 2007
A Kong
Summary Magnetic resonance imaging is an excellent technique for imaging the tendons and the ligaments of the ankle. Owing to the advantage of detailed demonstration of soft-tissue structures and capability for multiplanar demonstration of the ankle ligaments and tendons, MRI has been increasingly used in the evaluation of the ligamentous and the tendon injuries of the ankle. Knowledge of normal anatomy and of MRI appearances are essential to recognize pathological appearances. In this pictorial essay, the first of a three part series, we review the normal MRI appearances of the ankle tendons and ligaments. The anterior, lateral and medial tendon groups, the Achilles tendon and the lateral, the syndesmotic and the medial ligament groups are described and illustrated. Anatomy of the sinus tarsi is also described. Tendon and ligament pathology will be illustrated in the second part of the series, and imaging approach to ankle injuries will be outlined in the final part of this series. [source]

US Health Care Reform and Transplantation.

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2010
Impact on Access, Part I: Overview, Reimbursement in the Private Sector
The Health Care Reform (HCR) legislation passed by Congress in 2010 will have significant impact on transplant centers, patients and health care professionals. The Act seeks to expand coverage, limit the growth in health care costs and reform the delivery and insurance systems. In Part I of this two part series, we provide an overview and perspective of changes in private health insurance resulting from HCR. Under the plan, all Americans will be required to purchase coverage through their employer or via an improved individual/small group market. This legislation limits abusive practices such as limitations on preexisting conditions, lifetime and annual coverage limitations and dropping of beneficiaries if they become sick. The legislation will also limit high-cost plans and regulate premium increases. Private sector reforms are likely to benefit our patients by increasing the number of patients with access to transplant services, since the use of ,preexisting' conditions will be eliminated. However without a concomitant increase in the organ supply, longer waiting times and greater use of marginal organs are likely to increase the cost of transplant. Furthermore, transplant providers will receive reduced reimbursement as a result of market consolidation and the growing power of large transplant networks. [source]