3,182 research outputs found

    AutoAccel: Automated Accelerator Generation and Optimization with Composable, Parallel and Pipeline Architecture

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    CPU-FPGA heterogeneous architectures are attracting ever-increasing attention in an attempt to advance computational capabilities and energy efficiency in today's datacenters. These architectures provide programmers with the ability to reprogram the FPGAs for flexible acceleration of many workloads. Nonetheless, this advantage is often overshadowed by the poor programmability of FPGAs whose programming is conventionally a RTL design practice. Although recent advances in high-level synthesis (HLS) significantly improve the FPGA programmability, it still leaves programmers facing the challenge of identifying the optimal design configuration in a tremendous design space. This paper aims to address this challenge and pave the path from software programs towards high-quality FPGA accelerators. Specifically, we first propose the composable, parallel and pipeline (CPP) microarchitecture as a template of accelerator designs. Such a well-defined template is able to support efficient accelerator designs for a broad class of computation kernels, and more importantly, drastically reduce the design space. Also, we introduce an analytical model to capture the performance and resource trade-offs among different design configurations of the CPP microarchitecture, which lays the foundation for fast design space exploration. On top of the CPP microarchitecture and its analytical model, we develop the AutoAccel framework to make the entire accelerator generation automated. AutoAccel accepts a software program as an input and performs a series of code transformations based on the result of the analytical-model-based design space exploration to construct the desired CPP microarchitecture. Our experiments show that the AutoAccel-generated accelerators outperform their corresponding software implementations by an average of 72x for a broad class of computation kernels

    Does e-commerce reduce traffic congestion? Evidence from Alibaba single day shopping event

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    Traditional retail involves traffic both from warehouses to stores and from consumers to stores. Ecommerce cuts intermediate traffic by delivering goods directly from the warehouses to the consumers. Although plenty of evidence has shown that vans that are servicing e-commerce are a growing contributor to traffic and congestion, consumers are also making fewer shopping trips using vehicles. This poses the question of whether e-commerce reduces traffic congestion. The paper exploits the exogenous shock of an influential online shopping retail discount event in China (similar to Cyber Monday), to investigate how the rapid growth of e-commerce affects urban traffic congestion. Portraying e-commerce as trade across cities, I specified a CES demand system with heterogeneous consumers to model consumption, vehicle demand and traffic congestion. I tracked hourly traffic congestion data in 94 Chinese cities in one week before and two weeks after the event. In the week after the event, intra-city traffic congestion dropped by 1.7% during peaks and 1% during non-peak hours. Using Baidu Index (similar to Google Trends) as a proxy for online shopping, I found online shopping increasing by about 1.6 times during the event. Based on the model, I find evidence for a 10% increase in online shopping causing a 1.4% reduction in traffic congestion, with the effect most salient from 9am to 11am and from 7pm to midnight. A welfare analysis conducted for Beijing suggests that the congestion relief effect has a monetary value of around 239 million dollars a year. The finding suggests that online shopping is more traffic-efficient than offline shopping, along with sizable knock-on welfare gains

    Novel Therapeutic Targets for Ph+ Chromosome Leukemia and Its Leukemia Stem Cells: A Dissertation

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    The human Philadelphia chromosome (Ph) arises from a translocation between chromosomes 9 and 22 [t(9;22)(q34;q11)]. The resulting chimeric BCR-ABLoncogene encodes a constitutively activated, oncogenic tyrosine kinase that induces chronic myeloid leukemia (CML) and B-cell acute lymphoblastic leukemia (B-ALL). The BCR-ABL tyrosine kinase inhibitor (TKI), imatinib mesylate, induces a complete hematologic and cytogenetic response in the majority of CML patients, but is unable to completely eradicate BCR-ABL–expressing leukemic cells, suggesting that leukemia stem cells are not eliminated. Over time, patients frequently become drug resistant and develop progressive disease despite continued treatment. Two major reasons cause the imatinib resistance. The first one is the BCR-ABL kinase domain mutations which inhibit the interaction of BCR-ABL kinase domain with imatinib; the second one is the residual leukemia stem cells (LSCs) in the patients who are administrated with imatinib. To overcome these two major obstacles in CML treatment, new strategies need further investigation. As detailed in Chapter II, we evaluated the therapeutic effect of Hsp90 inhibition by using a novel water-soluble Hsp90 inhibitor, IPI-504, in our BCR-ABL retroviral transplantation mouse model. We found that BCR-ABL mutants relied more on the HSP90 function than WT BCR-ABL in CML. More interestingly, inhibition of HSP90 in CML leukemia stem cells with IPI-504 significantly decreases the survival and proliferation of CML leukemia stem cells in vitro and in vivo. Consistent with these findings, IPI-504 treatment achieved significant prolonged survival of CML and B-ALL mice. IPI-504 represents a novel therapeutic approach whereby inhibition of Hsp90 in CML patients and Ph+ ALL may significantly advance efforts to develop a cure for these diseases. The rationale underlying the use of IPI-504 for kinase inhibitor–resistant CML has implications for other cancers that display oncogene addiction to kinases that are Hsp90 client proteins. Although we proved that inhibition of Hsp90 could restrain LSCs in vitro and in vivo, it is still unclear how to define specific targets in LSCs and eradicate LSCs. In Chapter III, we took advantage of our CML mouse model and compared the global gene expression signature between normal HSCs and LSCs to identify the downregulation of Pten in CML LSCs. CML develops faster when Pten is deleted in Ptenfl/fl mice. On the other hand, Pten overexpression significantly delays the CML development and impairs leukemia stem cell function. mTOR is a major downstream of Pten-Akt pathway and it is always activated or overepxressed when Pten is mutated or deleted in human cancers. In our study, we found that inhibition of mTOR by rapamycin inhibited proliferation and induced apoptosis of LSCs. Notably, our study also confirmed a recent clinical report that Pten has been downregulated in human CML patient LSCs. In summary, our results proved the tumor suppressor role of Pten in CML mouse model. Although the mechanisms of Pten in leukemia stem cells still need further study, Pten and its downstream, such as Akt and mTOR, should be more attractive in LSCs study

    Modulated Unit-Norm Tight Frames for Compressed Sensing

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    In this paper, we propose a compressed sensing (CS) framework that consists of three parts: a unit-norm tight frame (UTF), a random diagonal matrix and a column-wise orthonormal matrix. We prove that this structure satisfies the restricted isometry property (RIP) with high probability if the number of measurements m=O(slog2slog2n)m = O(s \log^2s \log^2n) for ss-sparse signals of length nn and if the column-wise orthonormal matrix is bounded. Some existing structured sensing models can be studied under this framework, which then gives tighter bounds on the required number of measurements to satisfy the RIP. More importantly, we propose several structured sensing models by appealing to this unified framework, such as a general sensing model with arbitrary/determinisic subsamplers, a fast and efficient block compressed sensing scheme, and structured sensing matrices with deterministic phase modulations, all of which can lead to improvements on practical applications. In particular, one of the constructions is applied to simplify the transceiver design of CS-based channel estimation for orthogonal frequency division multiplexing (OFDM) systems.Comment: submitted to IEEE Transactions on Signal Processin

    Bis(1-methyl­piperazine-1,4-diium) tetra­chloridocuprate(II)

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    The title compound, (C5H14N2)[CuCl4], was synthesized by hydro­thermal reaction of CuCl2 with 1-methyl­piperazine in an HCl/water solution. Both amine N atoms are protonated. The piperazine ring adopts a chair conformation. The Cu—Cl distances in the tetrahedral anion are in the range 2.2360 (7)–2.2732 (7) Å. In the crystal, moderately strong and weak inter­molecular N—H⋯Cl hydrogen bonds link the anion and cation units into an infinite two-dimensional network parallel to the ab plane

    BcB_c Exclusive Decays to Charmonium and a Light Meson at Next-to-Leading Order Accuracy

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    In this paper the next-to-leading order (NLO) corrections to BcB_c meson exclusive decays to S-wave charmonia and light pseudoscalar or vector mesons, i.e. π\pi, KK, ρ\rho, and KK^*, are performed within non-relativistic (NR) QCD approach. The non-factorizable contribution is included, which is absent in traditional naive factorization (NF). And the theoretical uncertainties for their branching ratios are reduced compared with that of direct tree level calculation. Numerical results show that NLO QCD corrections markedly enhance the branching ratio with a K factor of 1.75 for Bc±ηcπ±B_{c}^{\pm}\to \eta_{c} \pi^{\pm} and 1.31 for Bc±J/ψπ±B_{c}^{\pm}\to J/\psi \pi^{\pm}. In order to investigate the asymptotic behavior, the analytic form is obtained in the heavy quark limit, i.e. mbm_b \to \infty. We note that annihilation topologies contribute trivia in this limit, and the corrections at leading order in z=mc/mbz= m_c/m_b expansion come from form factors and hard spectator interactions. At last, some related phenomenologies are also discussed.Comment: 20 pages, 7 figures and 5 table

    Robustness of a Blind Image Watermark Detector Designed by Orthogonal Projection

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    Blind digital watermarking, which can detect watermark without using the original image, is a key technique practical intellectual property protecting systems and concealment correspondence systems. In this paper, we discussed a blind detection method for the digital image watermark. The theories research show that the orthogonal projection sequence of a digital image is one-to-one correspondence with this digital image. To make use of this conclusion, we designed and realized a kind of blind watermark detector with the good performance. To calculate the correlation value between the image and watermark, the intensity information of digital image is not adopted, but the orthogonal projection sequence of this image is adopted. Experiment results show that this watermark detector not only to have very strong resistant ability to translation and rotation attacks, but also to have the good robustness to Gaussian noise. Performance of this watermark detector is better than general detector designed by making use of the intensity information directly. The conclusions obtained by experiments are useful to the research in the future

    An Empirical Study on Identification of Corporate Life Cycle Phases

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    This paper classifies corporate life cycle in four stages, from start-up, through growth, maturity and deline. 762 listed manufactory corporations have been used as sample in empirical analysis methodology. Profit margin is chosen as the fundamental index first, then the index of development trend that based on comparing with average similar companies in this industry is constructed. According to those indexes that are chosen from half time of the whole corporate life cycle, we can demonstrate that what kind of life cycle phases are corporations at
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