High performance fault tolerance through predictive instruction re-execution

Processor designers face the challenge of defect formation, leading to permanent faults, during fabrication and operation. Permanent or hard fault tolerance is an important problem in computing systems, solutions to which can help improve yield during fabrication and reduce the cost of transistor mortality during the service life of the processor. This paper presents PreFix, a method to handle hard errors to keep a faulty core running and correctly executing instructions. Instead of turning off faulty structures, PreFix predicts early on whether an instruction is likely to use faulty components, then refines this prediction later in the pipeline to actually detect when an error has occurred. Instructions marked as possibly- faulty in the front-end are queued for duplicate execution on a separate core. At commit, results from the original and duplicate instructions are compared. Upon a mismatch, the original instruction is patched up, the pipeline flushed and execution continues. Using PreFix, faulty components can continue performing useful work when their errors do not manifest in architecturally visible state changes. This enhances processor lifetime with minimal performance overhead

Development of EM-CCD-based X-ray detector for synchrotron applications

A high speed, low noise camera system for crystallography and X-ray imaging applications is developed and successfully demonstrated. By coupling an electron-multiplying (EM)-CCD to a 3:1 fibre-optic taper and a CsI(Tl) scintillator, it was possible to detect hard X-rays. This novel approach to hard X-ray imaging takes advantage of sub-electron equivalent readout noise performance at high pixel readout frequencies of EM-CCD detectors with the increase in the imaging area that is offered through the use of a fibre-optic taper. Compared with the industry state of the art, based on CCD camera systems, a high frame rate for a full-frame readout (50 ms) and a lower readout noise (<1 electron root mean square) across a range of X-ray energies (6–18 keV) were achieved

Codification challenges for data science in construction

New forms of data science, including machine learning and data analytics, are enabled by machine-readable informationbut are not widely deployed in construction. Aqualitative study of information flow in three projects usingBuilding Information Modelling (BIM) in the late designand construction phaseis used to identify the challenges of codification whichlimit the application of data science.Despite substantial efforts to codify information with ‘Common Data Environment(CDE)’ platforms to structure and transfer digital information within and between teams, participants work across multiple media in both structured and unstructured ways. Challenges of codification identified in this paper relate to software usage (interoperability, translation, modelling, and file-based sharing), information sharing (unstructured information, document control, workarounds, process change,and multiple CDEs), and construction process information(loss of constraints and low level of detail). This paper contributes to the current understanding of data science in construction by articulating the codification challenges and their implications for data quality dimensions,such as accuracy, completeness, accessibility, consistency, timeliness, and provenance.It concludes with practical implications for developingand using machine-readable information and directions for research to extract insight from data and support future automation

Realization of perfect reconstruction non-uniform filter banks via a tree structure

Obviously, a tree structure filter bank can be realized via a non-uniform filter bank, and perfect reconstruction is achieved if and only if each branch of the tree structure can provide perfect reconstruction. In this paper, the converse of this problem is studied. We show that a perfect reconstruction non-uniform filter bank with decimation ratio {2,4,4} can be realized via a tree structure and each branch of the tree structure achieves perfect reconstruction

Analysis of Dual Phase Dual Stage Boost Converter for Photovoltaic Applications

In the previous two decades, the depletion of fossil fuels has led to applications with renewable energy sources. The approach for renewable energy application is to achieve eminent static boost ratio from with miniaturized ripple content in both current and voltage. The novel converter discussed in this paper is derived by combining the concept of interleaving and cascading of boost converters. The presented design has a dual phase boost converter followed by a stage of boost converter which as a whole acts like dual phase dual stage boost converter. The interleaving concept is utilized in dual phase boost converter to reduce the voltage current stress created in boosting process and its output is boosted by the dual stage boost converter which improves overall efficiency with respect to the existing systems. The converter is designed for a power rating of 200W with output voltage of 192V for an input voltage of 12V obtained from photovoltaic source at a switching frequency of 50KHz this illustrate the advantages over other existing converters . The different parameters of the proposed boost converter are contrasted with that of a conventional boost converter. Furthermore, the simulations results of the proposed converter are presented to validate the system design. The results exhibit that this converter achieves a predominant performance over other dc-dc boost converters by offering improved efficiency and voltage gain, while having lower input current ripple

REPAIR: Hard-error recovery via re-execution

Processor reliability at upcoming technology nodes presents significant challenges to designers from increased manufacturing variability, parametric variation and transistor wear-out leading to permanent faults. We present a design to tolerate this impact at the microarchitectural level—a chip with n cores together with one or more shared instruction re-execution units (IRUs). Instructions using a faulty component are identified and re-executed on an IRU. This design incurs no slowdown in the absence of errors and allows continued operation of all n cores after multiple hard errors on one or all cores in the structures protected by our scheme. Experiments show that a single-core chip experiences only a 23% slowdown with 1 error, rising to 43% in the presence of 5 errors. In a 4-core scenario with 4 errors on every core and a shared IRU, REPAIR enables performance of 0.68× of a fully functioning system.This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) through grants EP/K026399/1 and EP/J016284/1. Experiments used the Darwin Supercomputer of the University of Cambridge High Performance Computing Service (http://www.hpc.cam.ac.uk/) funded by the Higher Education Funding Council for England and the Science and Technology Facilities Council.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/DFT.2015.731513

Evaluation of efficacy and safety of Bacillus coagulans SNZ 1969 supplementation for irritable bowel syndrome: a randomized, double-blind, placebo-controlled study

Background: Probiotic potential (efficacy and safety) of Bacillus coagulans SNZ 1969 has been studied in patients with constipation-predominant irritable bowel syndrome (IBS-C) and-diarrhea predominant IBS (IBS-D).Methods: This randomized, double-blind, two-arm, placebo-controlled parallel study randomized 92 patients (1:1) to receive either 500 million CFU of Bacillus coagulans SNZ 1969 (treatment group) or placebo (placebo group) twice daily for 60 days under two subtypes of IBS, IBS-D (n=46) and IBS-C (n=46). Primary outcomes were changes in IBS symptom severity noted using the gastrointestinal symptom rating scale-IBS version (GSRS-IBS) on days 30, 60, and 75, and the number of treatment responders defined by subject’s global assessment (SGA) of relief ≤3 and ≤2 at days 30 and 60, respectively. We also assessed patient’s quality of life.Results: The GSRS-IBS scores reduced from day 30 through 75 in both IBS groups treated with Bacillus coagulans SNZ1969 compared to placebo (p<0.05). Higher GSRS-IBS score was noted in patients with IBS-C in the treatment group (22.45±2.7) than the placebo group (3.55±3.02; p<0.0001), and this trend was similar in IBS-D patients (p<0.0001). Most patients (90%) with IBS-C and all with IBS-D responded to Bacillus coagulans SNZ 1969 compared to no responders with placebo (p<0.0001). The SF-8 scores significantly reduced in patients receiving Bacillus coagulans SNZ 1969 than placebo for both IBS subtypes. One adverse event unrelated to the study treatments was reported in IBS-D group.Conclusions: Bacillus coagulans SNZ 1969 is safe, effective in alleviating IBS-associated clinical symptoms, and improves quality of life

Plasma Cross-Gestational Sphingolipidomic Analyses Reveal Potential First Trimester Biomarkers of Preeclampsia

Introduction Preeclampsia (PE) is a gestational disorder, manifested in the second half of pregnancy by maternal hypertension, proteinuria and generalized edema. PE is a major cause of maternal and fetal morbidity and mortality, accounting for nearly 40% of all premature births worldwide. Bioactive sphingolipids are emerging as key molecules involved in etiopathogenesis of PE, characterized by maternal angiogenic imbalance and symptoms of metabolic syndrome. The aim of this study was to compare the cross-gestational profile of circulating bioactive sphingolipids in maternal plasma from preeclamptic (PE) versus normotensive control (CTL) subjects with the goal of identifying sphingolipids as candidate first trimester biomarkers of PE for early prediction of the disease. Methods A prospective cohort of patients was sampled at the first, second and third trimester of pregnancy for each patient (11–14, 22–24, and 32–36 weeks´ gestation). A retrospective stratified study design was used to quantify different classes of sphingolipids in maternal plasma. We used a reverse-phase high-performance liquid chromatography-tandem mass spectrometry (HPLC-ESI-MS/MS) approach for determining different sphingolipid molecular species (sphingosine-1-phosphate (S1P), dihydro-sphingosine-1-phosphate (DH-S1P), sphingomyelins (SM) and ceramides (Cer)) in cross-gestational samples of human plasma from PE (n = 7, 21 plasma samples across pregnancy) and CTL (n = 7, 21 plasma samples across pregnancy) patients. Results Plasma levels of angiogenic S1P did not change significantly in control and in preeclamptic patients´ group across gestation. DH-S1P was significantly decreased in second trimester plasma of PE patients in comparison to their first trimester, which could contribute to reduced endothelial barrier observed in PE. The major ceramide species (Cer 16:0 and Cer 24:0) tended to be up-regulated in plasma of control and PE subjects across gestation. The levels of a less abundant plasma ceramide species (Cer 14:0) were significantly lower in first trimester plasma of PE patients when compared with their gestational-matched control samples (p = 0.009). Major plasma sphingomyelin species (SM 16:0, SM 18:1 and SM 24:0) tended to be higher in control pregnancies across gestation. However, in PE patients, SM 16:0, SM 18:0 and SM 18:1 showed significant up-regulation across gestation, pointing to atherogenic properties of the sphingomyelins and particularly the potential contribution of SM 18:0 to the disease development. In addition, two major sphingomyelins, SM 16:0 and SM 18:0, were significantly lower in first trimester plasma of PE patients versus first trimester samples of respective controls (p = 0.007 and p = 0.002, respectively). Conclusions Cross-gestational analysis of maternal plasma of preeclamptic and normotensive women identifies differences in the biochemical profile of major sphingolipids (DH-S1P, sphingomyelins and ceramides) between these two groups. In addition, first trimester maternal plasma sphingolipids (Cer 14:0, SM 16:0 and SM 18:0) may serve in the future as early biomarkers of PE occurrence and development

Improving radiation hardness in space-based Charge-Coupled Devices through the narrowing of the charge transfer channel

Charge-Coupled Devices (CCDs) have been the detector of choice for imaging and spectroscopy in space missions for several decades, such as those being used for the Euclid VIS instrument and baselined for the SMILE SXI. Despite the many positive properties of CCDs, such as the high quantum efficiency and low noise, when used in a space environment the detectors suffer damage from the often-harsh radiation environment. High energy particles can create defects in the silicon lattice which act to trap the signal electrons being transferred through the device, reducing the signal measured and effectively increasing the noise. We can reduce the impact of radiation on the devices through four key methods: increased radiation shielding, device design considerations, optimisation of operating conditions, and image correction. Here, we concentrate on device design operations, investigating the impact of narrowing the charge-transfer channel in the device with the aim of minimising the impact of traps during readout. Previous studies for the Euclid VIS instrument considered two devices, the e2v CCD204 and CCD273, the serial register of the former having a 50 μm channel and the latter having a 20 μm channel. The reduction in channel width was previously modelled to give an approximate 1.6× reduction in charge storage volume, verified experimentally to have a reduction in charge transfer inefficiency of 1.7×. The methods used to simulate the reduction approximated the charge cloud to a sharp-edged volume within which the probability of capture by traps was 100%. For high signals and slow readout speeds, this is a reasonable approximation. However, for low signals and higher readout speeds, the approximation falls short. Here we discuss a new method of simulating and calculating charge storage variations with device design changes, considering the absolute probability of capture across the pixel, bringing validity to all signal sizes and readout speeds. Using this method, we can optimise the device design to suffer minimum impact from radiation damage effects, here using detector development for the SMILE mission to demonstrate the process