Brain-inspired spiking neural network (SNN) has recently attracted widespread interest owing to its event-driven nature and relatively low-power hardware for transmitting highly sparse binary spikes. To further improv...
详细信息
Brain-inspired spiking neural network (SNN) has recently attracted widespread interest owing to its event-driven nature and relatively low-power hardware for transmitting highly sparse binary spikes. To further improve energy efficiency, some matrix compression algorithms are used for weight storage. However, the weight sparsity of different layers varies greatly. For a multicore neuromorphic system, it is difficult for the same compression algorithm to adapt to all the layers of SNN model. In this work, we propose a weight density adaptation architecture with hybrid compression method for SNN, named Marmotini. It is a multicore heterogeneous design, including three types of cores to complete computation of different weight sparsity. Benefiting from the hybrid compression method, Marmotini minimizes the waste of neurons and weights as much as possible. Besides, for better flexibility, a reconfigurable core that can be configured to compute convolutional layer or fully connected layer is proposed. Implemented on Xilinx Kintex UltraScale XCKU115 field-programmable gate array (FPGA) board, Marmotini can operate at 150-MHz frequency, achieving 244.6-GSOP/s peak performance and 54.1-GSOP/W energy efficiency at 0% spike sparsity.
We present displacement estimated interframe (DEI) coding, a new coding scheme for 3-D medical image data sets such as x-ray CT or MR images. To take advantage of the correlation between contiguous slices, a displacem...
详细信息
We present displacement estimated interframe (DEI) coding, a new coding scheme for 3-D medical image data sets such as x-ray CT or MR images. To take advantage of the correlation between contiguous slices, a displacement-compensated difference image based on the previous image is encoded. We have determined the best fitting distribution functions for the discrete cosine transform (DCT) coefficients obtained from displacement compensated difference images, and used the results in allocating bits and optimizing quantizers for the coefficients. The DEI scheme is compared with a 2-D block DCT as well as a full-frame DCT using the bit allocation technique by Lo and Huang [1]. For x-ray CT head images, our bit allocation and quantizer design using an appropriate distribution model resulted in a 13 dB improvement in the SNR compared to the full-frame DCT using the bit allocation technique. For an image set with 5 mm slice thickness, the DEI method compared to the 2-D block DCT gave about 5 percent improvement in the compression ratio on average and less blockiness at the same distortion. The performance gain increases to about 10 percent when the slice thickness decreases to 3 mm.
We present a novel technique for the design of filters for random noise, leading to a class of filters called Occam filters. The essence of the technique is that when a lossy data compression algorithm is applied to a...
详细信息
We present a novel technique for the design of filters for random noise, leading to a class of filters called Occam filters. The essence of the technique is that when a lossy data compression algorithm is applied to a noisy signal with the allowed loss set equal to the noise strength, the loss and the noise tend to cancel rather than add. We give two illustrative applications of the technique to univariate signals. We also prove asymptotic convergence bounds on the effectiveness of Occam filters.
This paper investigates data compression that simultaneously allows local decoding and local update. The main result is a universal compression scheme for memoryless sources with the following features. The rate can b...
详细信息
This paper investigates data compression that simultaneously allows local decoding and local update. The main result is a universal compression scheme for memoryless sources with the following features. The rate can be made arbitrarily close to the entropy of the underlying source, contiguous fragments of the source can be recovered or updated by probing or modifying a number of codeword bits that is on average linear in the size of the fragment, and the overall encoding and decoding complexity is quasilinear in the blocklength of the source. In particular, the local decoding or update of a single message symbol can be performed by probing or modifying on average a constant number of codeword bits. This latter part improves over previous best known results for which local decodability or update efficiency grows logarithmically with blocklength.
In recent years, there have been a number of studies addressing both reversible and irreversible compression of medical images ranging from 256 x 256 to 2048 x 2048 pixels in spatial resolution. There is a need to add...
详细信息
In recent years, there have been a number of studies addressing both reversible and irreversible compression of medical images ranging from 256 x 256 to 2048 x 2048 pixels in spatial resolution. There is a need to address the high-resolution end of the image categories, namely mammograms and chest X-rays, which require resolution of the order of 4096 x 4096 pixels. Further, data compression schemes for most medical applications have to be information-preserving or reversible. In this paper, the performance of a number of block-based, reversible, compression algorithms suitable for compression of very large-format images (4096 x 4096 pixels or more) is compared to that of a novel two-dimensional linear predictive coder developed by extending the multichannel version of the Burg algorithm to two dimensions. The compression schemes implemented are: Huffman coding, Lempel-Ziv coding, arithmetic coding, two-dimensional linear predictive coding (in addition to the aforementioned one), transform coding using discrete Fourier-, discrete cosine-, and discrete Walsh transforms, linear interpolative coding, and combinations thereof. We discuss the performance of these coding techniques with a few mammograms and chest radiographs digitized to sizes up to 4096 x 4096, 10 b pixels. We have achieved compression from 10 bits to 2.5-3.0 b/pixel on these images without any loss of information. The modified multichannel linear predictor out-performs the other methods while offering certain advantages in implementation.
With the development of deep learning, neural networks are widely used in various fields, and the improved model performance also introduces a considerable number of parameters and computations. Model quantisation is ...
详细信息
With the development of deep learning, neural networks are widely used in various fields, and the improved model performance also introduces a considerable number of parameters and computations. Model quantisation is a technique that turns floating-point computing into low-specific-point computing, which can effectively reduce model computation strength, parameter size, and memory consumption but often bring a considerable loss of accuracy. This paper mainly addresses the problem where the distribution of parameters is too concentrated during quantisation aware training (QAT). In the QAT process, we use a piecewise function to statistics the parameter distributions and simulate the effect of quantisation noise in each round of training, based on the statistical results. Experimental results show that by quantising the Transformer network, we lose less precision and significantly reduce the storage cost of the model;compared with the full precision LSTM network, our model has higher accuracy under the condition of a similar storage cost. Meanwhile, compared with other quantisation methods on language modelling task, our approach is more accurate. We validated the effectiveness of our policy on the WikiText-103 and PENN Treebank datasets. The experiments show that our method extremely compresses the storage cost and maintains high model performance.
Stream processing has been in widespread use, and one of the most common application scenarios is SQL query on streams. By 2021, the global deployment of IoT endpoints reached 12.3 billion, indicating a surge in data ...
详细信息
Stream processing has been in widespread use, and one of the most common application scenarios is SQL query on streams. By 2021, the global deployment of IoT endpoints reached 12.3 billion, indicating a surge in data generation. However, the escalating demands for high throughput and low latency in stream processing systems have posed significant challenges due to the increasing data volume and evolving user requirements. We present a compression-based stream processing engine, called CompressStreamDB, which enables adaptive fine-grained stream processing directly on compressed streams, to significantly enhance the performance of existing stream processing solutions. CompressStreamDB utilizes nine diverse compression methods tailored for different stream data types and integrates a cost model to automatically select the most efficient compression schemes. CompressStreamDB provides high throughput with low latency in stream SQL processing by identifying and eliminating redundant data among streams. Our evaluation demonstrates that CompressStreamDB improves average performance by 3.84x and reduces average delay by 68.0% compared to the state-of-the-art stream processing solution for uncompressed streams, along with 68.7% space savings. Besides, our edge trials show an average throughput/price ratio of 9.95x and a throughput/power ratio of 7.32x compared to the cloud design.
Large bilingual parallel texts (also known as bitexts) are usually stored in a compressed form, and previous work has shown that they can be more efficiently compressed if the fact that the two texts are mutual transl...
详细信息
Large bilingual parallel texts (also known as bitexts) are usually stored in a compressed form, and previous work has shown that they can be more efficiently compressed if the fact that the two texts are mutual translations is exploited. For example, a bitext can be seen as a sequence of biwords pairs of parallel words with a high probability of co-occurrence that can be used as an intermediate representation in the compression process. However, the simple biword approach described in the literature can only exploit one-to-one word alignments and cannot tackle the reordering of words. We therefore introduce a generalization of biwords which can describe multi-word expressions and reorderings. We also describe some methods for the binary compression of generalized biword sequences, and compare their performance when different schemes are applied to the extraction of the biword sequence. In addition, we show that this generalization of biwords allows for the implementation of an efficient algorithm to look on the compressed bitext for words or text segments in one of the texts and retrieve their counterpart translations in the other text-an application usually referred to as translation spotting-with only some minor modifications in the compression algorithm.
LZ77 is a dictionary compression algorithm by replacing the repeating sequence with the addresses of the previous referenced data in the stream. To find out these repetition, the LZ77 encoder maintains a hashing table...
详细信息
LZ77 is a dictionary compression algorithm by replacing the repeating sequence with the addresses of the previous referenced data in the stream. To find out these repetition, the LZ77 encoder maintains a hashing table, which have to frequently calculate hash values during the encoding process. In this paper, we present a class of rolling hash functions, that can calculate multiple hash values via a carry-less multiplication instruction. Then the proposed hash function is implemented in LZ4, which is a derivative of LZ77. The simulation shows that the encoding throughput of LZ4 has 15.7% improvement in average, and the compression ratio is +/- 1% in most cases.
The trajectory data of vessel AIS (automatic identification system) has important theoretical and application value for information supporting decisions. However, large sizes lead to difficulties in storing, querying,...
详细信息
The trajectory data of vessel AIS (automatic identification system) has important theoretical and application value for information supporting decisions. However, large sizes lead to difficulties in storing, querying, and processing. To solve the problems of high compression ratio and longtime consumption of the existing online trajectory compression algorithm, an SPM (scan-pick-move) trajectory data compression algorithm added sliding window is proposed. In order to better compress vessel trajectory data regarding compression efficiency, the sliding window is added to the classical SPM algorithm. In order to reduce trajectory data storage space, the maximum offset distance reference trajectory point is used as the criterion of whether the current trajectory point can be compressed. In this paper, the multi-dimensional space-time characteristics of trajectory data, such as distance error, compression ratio and compression time, are selected to evaluate the trajectory compression method from three levels: geometric characteristics, motion characteristics and compression efficiency. Compared with the existing SPM trajectory data compression algorithm, parallel experiments are conducted based on AIS data gathered over the duration of a month in the Japan Osaka Bay. The SPM trajectory compression algorithm added sliding window can significantly reduce the compression time and outperforms other existing trajectory compression algorithms in term of average compression error at high compression strengths. Also, the proposed method has high compression efficiency in the range of commonly used compression thresholds.
暂无评论