The power lithium-ion battery with its high specific energy, high theoretical capacity
and good cycle-life is a prime candidate as a power source for electric vehicles (EVs)
and hybrid electric vehicles (HEVs). Safety is especially important for large-scale
lithium-ion batteries, especially the thermal analysis is essential for their development
and design. Thermal modeling is an effective way to understand the thermal behavior
of the lithium-ion battery during charging and discharging. With the charging and
discharging, the internal heat generation of the lithium-ion battery becomes large, and
the temperature rises leading to an uneven temperature distribution induces partial
degradation. Infrared (IR) Non-destructive Evaluation (NDE) has been well
developed for decades years in materials, structures, and aircraft. Most thermographic
methods need thermal excitation to the measurement structures. In NDE of battery,
the thermal excitation is the heat generated from carbon and cobalt electrodes in
electrolyte. A technique named "power function" has been developed to determine the
heat by chemical reactions.
In this paper, the simulations of the transient response of the temperature distribution
in the lithium-ion battery are developed. The key to resolving the security problem
lies in the thermal controlling, including the heat generation and the internal and
external heat transfer. Therefore, three-dimensional modelling for capturing
geometrical thermal effects on battery thermal abuse behaviour is required. The
simulation model contains the heat generation during electrolyte decomposition and
electrical resistance component. Oven tests are simulated by three-dimensional model
and the discharge test preformed by test system. Infrared thermography of discharge
is recorded in order to analyze the security of the lithium-ion power battery.
Nondestructive detection is performed for thermal abuse analysis and discharge
analysis.
KEYWORDS: Databases, Computer simulations, Roads, Associative arrays, Explosives, Data processing, Lithium, Current controlled current source, Multiplexing, Computing systems
Parallelism of spatial index could significantly improve the performance of spatial queries, special for massive spatial
databases, so the research of parallel spatial index takes a important role in high performance spatial databases. Existing
parallel spatial index methods have two main shortcoming: one is accessing hotspot and bottleneck of index items
located in main server, the other is high costs and complicated operations for maintaining index consistency. Aim at
these, a distributed parallel spatial index structure called DPR-tree is proposed. It splits whole index region into partition
sub-regions by using Hilbert space-filling curve grid and organizes index sub-regions according to locality of spatial
objects, then maps index sub-regions to partition sub-regions and assigns these index sub-regions to different computer
nodes by a appointed map function, Each computer node manages a multi-level distributed sub-Rtree which is built from
a index sub-region. Our experimental results indicate that the proposed parallel spatial index can achieve speedup well
and offer significant potential for reducing query response time.
KEYWORDS: Visibility, 3D modeling, Buildings, Image segmentation, Algorithm development, Visualization, 3D visualizations, 3D applications, Performance modeling, Geographic information systems
At present, Cybercity has introduced the visualization f 3D buildings, and the further development necessarily includes various applications of 3D scenes from outdoor to indoor. Nevertheless, as a large furnished 3D architectural model is usually made up of millions of polygons, ideal frame rates for smooth interactive walkthroughs are hardly available. Visibility processing for potentially visible set of polygons (PVS) is of great importance in improving performance for interactive indoor walkthroughs. A novel algorithm of constructing room-to-room PVS and view-to-room PVS for various architectural structures, which may be concave, or non-axis-aligned, etc., is proposed in this paper. Test shows it can drastically improve the performance of real-time interactive walkthroughs in a large furnished architectural 3D model.
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