A space-efficient linear-time approximation algorithm for the grammar-based compression problem, which requests for a given string to find a smallest context-free grammar deriving the string, is presented. The algorithm consumes only O(g∗ log g∗) space and achieves the worstcase approximation ratio O(log g∗ log n), with the size n of an input and the optimum grammar size g∗. Experimental result...

Reducing instruction memory requirements by improving code density using compression techniques has been the aim of much recent work on embedded devices. Previous work has been successful in improving compression ratios with modest decompression overhead for general purpose RISC architectures. However, most traditional compression techniques fail to produce good results for tightly encoded VLIW...

A multichannel terrain observation by progressive scans (TOPS) synthetic aperture radar (SAR) system is capable of imaging a wider swath with a higher azimuth resolution for improved moving target detection. For TOPS SAR, due to antenna beam steering, the azimuth bandwidth of background clutter is much larger than the instantaneous signal bandwidth. To overcome this problem, a method referred t...

Database compression and decompression is a susceptible problem in the database framework. Database compression is widely used in data management to improve the performance and save storage space. When you have large amounts of data, the cost of the storage subsystem can easily exceed the cost of your data server. Over the last decades, improvements in CPU speed have outpaced improvements in ma...

this paper presents the design procedure and implementation results of a proposed hardware which performs different satellite image compressions using fpga xilinx board. first, the method is described and then vhdl code is written and synthesized by ise software of xilinx company. the results show that it is easy and useful to design, develop and implement the hardware image compressor using ne...

background & importance: primary hemifacial spasm is usually caused by microvascular compression of the facial nerve at its root exit zone at brainstem without any space-occupying pathology. secondary or so-called symptomatic hemifacial spasm has an additional underlying pathology e.g. tumors leading to the microvascular compression. we review and discuss the pathophysiology and the literature ...