Fast Min-Sum Algorithms for Decoding of LDPC over GF(q)

In this paper, we present a fast min-sum algorithm for decoding LDPC codes over GF(q). Our algorithm is different from the one presented by David Declercq and Marc Fossorier in ISIT 05 only at the way of speeding up the horizontal scan in the min-sum algorithm. The Declercq and Fossorier's algorithm speeds up the computation by reducing the number of configurations, while our algorithm uses the dynamic programming instead. Compared with the configuration reduction algorithm, the dynamic programming one is simpler at the design stage because it has less parameters to tune. Furthermore, it does not have the performance degradation problem caused by the configuration reduction because it searches the whole configuration space efficiently through dynamic programming. Both algorithms have the same level of complexity and use simple operations which are suitable for hardware implementations.Comment: Accepted by IEEE Information Theory Workshop, Chengdu, China, 200

An Exploratory Study of the Gap between Client Expectations and Client Perceived Performance of the Delivered Information System

This exploratory study is designed to answer “what happens when the clients complain that the delivered Information Systems (IS) don’t match their expectations?” This discrepancy between client expectations and the client perceived system performance at the time of system delivery can be described as a “gap”. The “gap” phenomenon, the failing to match client expectations with the delivered system, will lead to client dissatisfaction, system rejection, and project failure. Since we know little about the “gap” phenomenon, and no literature has directly and systematically investigated this phenomenon before, an exploratory qualitative study was conducted to answer (1) what the gap is; and (2) how and why the gap is generated in the IS development process. Focus group interviews were conducted with project managers, developers and consultants from four leading IS developing organizations. This paper reports the findings of the first part of the exploratory study. In this study, two dimensions of the gap – the possible areas of the gap and the forms of the gap are identified and four types of the gaps are classified based on the two dimensions. We then adopt a process view to investigate how the gap is generated in the IS development process. To assist the discussion and investigation, we defined four sub-gaps – requirements definition gap, system design gap, construction gap, and system delivery gap. Propositions are proposed and a gap model is developed to explain the relationship between the four sub-gaps and the final gap

Cost-Effectiveness of Electricity Energy Efficiency Programs: Demand-Side Management's (DSM) Future Role in Energy Markets and Feasibility of Smart Meters in New York City

Thesis advisor: Scott FulfordCan smart metering program and time-of-use (TOU) prices help reduce energy consumption in New York City? Being able to track electricity consumption levels and to modify consumer usage patterns are important for policy makers to efficiently manage the energy markets. Unfortunately, no reliable and up-to-date data have been brought to bear on this question. I study the effects of time-of-use (TOU) prices and smart metering for the residents of Shanghai and I investigate further what can policy makers do in order to adapt and transfer this successful DSM experience from Shanghai to the residential sector in New York City. The primary objective of my study is to characterize the realistic short-term and long-term potential for the smart metering program in New York City given my empirical findings that the smart metering program has had brought great benefits to the residents of Shanghai. People respond to incentives; if electricity is charged at different prices throughout a day, consumers are likely to shift their usage to when it is cheaper. My findings suggest that policy makers should think harder about designing a pricing scheme that can optimize the social plus.Thesis (BA) — Boston College, 2011.Submitted to: Boston College. College of Arts and Sciences.Discipline: College Honors Program.Discipline: Economics Honors Program.Discipline: Economics

Molecule Generation by Principal Subgraph Mining and Assembling

Molecule generation is central to a variety of applications. Current attention has been paid to approaching the generation task as subgraph prediction and assembling. Nevertheless, these methods usually rely on hand-crafted or external subgraph construction, and the subgraph assembling depends solely on local arrangement. In this paper, we define a novel notion, principal subgraph, that is closely related to the informative pattern within molecules. Interestingly, our proposed merge-and-update subgraph extraction method can automatically discover frequent principal subgraphs from the dataset, while previous methods are incapable of. Moreover, we develop a two-step subgraph assembling strategy, which first predicts a set of subgraphs in a sequence-wise manner and then assembles all generated subgraphs globally as the final output molecule. Built upon graph variational auto-encoder, our model is demonstrated to be effective in terms of several evaluation metrics and efficiency, compared with state-of-the-art methods on distribution learning and (constrained) property optimization tasks.Comment: Accepted by NeurIPS 202

Going Far Boosts Attack Transferability, but Do Not Do It

Deep Neural Networks (DNNs) could be easily fooled by Adversarial Examples (AEs) with an imperceptible difference to original ones in human eyes. Also, the AEs from attacking one surrogate DNN tend to cheat other black-box DNNs as well, i.e., the attack transferability. Existing works reveal that adopting certain optimization algorithms in attack improves transferability, but the underlying reasons have not been thoroughly studied. In this paper, we investigate the impacts of optimization on attack transferability by comprehensive experiments concerning 7 optimization algorithms, 4 surrogates, and 9 black-box models. Through the thorough empirical analysis from three perspectives, we surprisingly find that the varied transferability of AEs from optimization algorithms is strongly related to the corresponding Root Mean Square Error (RMSE) from their original samples. On such a basis, one could simply approach high transferability by attacking until RMSE decreases, which motives us to propose a LArge RMSE Attack (LARA). Although LARA significantly improves transferability by 20%, it is insufficient to exploit the vulnerability of DNNs, leading to a natural urge that the strength of all attacks should be measured by both the widely used $\ell_\infty$ bound and the RMSE addressed in this paper, so that tricky enhancement of transferability would be avoided

Synergetic Effect of Plasmonic Gold Nanorods and MgO for Perovskite Solar Cells

We report new structured perovskite solar cells (PSCs) using solution-processed TiO2/Au nanorods/MgO composite electron transport layers (ETLs). The proposed method is facile, convenient, and effective. Briefly, Au nanorods (NRs) were prepared and introduced into mesoporous TiO2 ETLs. Then, thin MgO overlayers were grown on the Au NRs modified ETLs by wet spinning and pyrolysis of the magnesium salt. By simultaneous use of Au NRs and MgO, the power conversion efficiency of the PSC device increases from 14.7% to 17.4%, displaying over 18.3% enhancement, compared with the reference device without modification. Due to longitudinal plasmon resonances (LPRs) of gold nanorods, the embedded Au NRs exhibit the ability to significantly enhance the near-field and far-field (plasmonic scattering), increase the optical path length of incident photons in the device, and as a consequence, notably improve external quantum efficiency (EQE) at wavelengths above 600 nm and power conversion efficiency (PCE) of PSC solar cells. Meanwhile, the thin MgO overlayer also contributes to enhanced performance by reducing charge recombination in the solar cell. Theoretical calculations were carried out to elucidate the PV performance enhancement mechanisms

Facile template-free synthesis of vertically aligned polypyrrole nanosheets on nickel foams for flexible all-solid-state asymmetric supercapacitors

This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window

Inhibition of Notch1 Signaling Alleviates Endotoxin-Induced Inflammation Through Modulating Retinal Microglia Polarization

Microglial cells are resident immune cells and play an important role in various cerebral and retinal inflammatory diseases. Notch1 signaling is involved in the microglia polarization and the control of cerebral inflammatory reactions. However, its role in endotoxin-induced uveitis (EIU) remains unknown. This study aimed to investigate the role of Notch1 signaling on retinal microglia polarization and inflammation in the cultured retinal microglial cells and EIU rat model. We found that Notch1 signaling blockade with N-[N-(3, 5-difluorophenacetyl)-1-alany1-S-phenyglycine t-butyl ester (DAPT) shifted retinal microglia phenotype from pro-inflammatory M1 phenotype (COX2+ and iNOS+) to anti-inflammatory M2 phenotype (Arg-1+) and reduced the release of pro-inflammatory cytokines both in vivo and in vitro. Moreover, DAPT treatment contributed to prevent retinal ganglion cells from apoptosis, reduce the intraocular infiltrating cells, and attenuate the impairment of retinal function. Taken together, these results suggest that inhibition of Notch1 signaling could alleviate the inflammatory response in EIU rat mainly through regulating the polarization of retinal microglia. Therefore, Notch1 signaling might be a promising therapeutic target in the treatment of ocular inflammatory diseases