Algorithm-Directed Crash Consistence in Non-Volatile Memory for HPC

Fault tolerance is one of the major design goals for HPC. The emergence of non-volatile memories (NVM) provides a solution to build fault tolerant HPC. Data in NVM-based main memory are not lost when the system crashes because of the non-volatility nature of NVM. However, because of volatile caches, data must be logged and explicitly flushed from caches into NVM to ensure consistence and correctness before crashes, which can cause large runtime overhead. In this paper, we introduce an algorithm-based method to establish crash consistence in NVM for HPC applications. We slightly extend application data structures or sparsely flush cache blocks, which introduce ignorable runtime overhead. Such extension or cache flushing allows us to use algorithm knowledge to \textit{reason} data consistence or correct inconsistent data when the application crashes. We demonstrate the effectiveness of our method for three algorithms, including an iterative solver, dense matrix multiplication, and Monte-Carlo simulation. Based on comprehensive performance evaluation on a variety of test environments, we demonstrate that our approach has very small runtime overhead (at most 8.2\% and less than 3\% in most cases), much smaller than that of traditional checkpoint, while having the same or less recomputation cost.Comment: 12 page

Handheld forward-imaging needle endoscope for ophthalmic optical coherence tomography inspection

We report the narrowest to-date (21 gauge, 820-µm-diam) handheld forward-imaging optical coherence tomography (OCT) needle endoscope and demonstrate its feasibility for ophthalmic OCT inspection. The probe design is based on paired-angle-rotation scanning (PARS), which enables a linear B-scan pattern in front of the probe tip by using two counterrotating angle polished gradient-index (GRIN) lenses. Despite its small size, the probe can provide a numerical apertune (NA) of 0.22 and an experimental sensitivity of 92 dB at 0.5 frames. The feasibility of retinal imaging is tested on enucleated ex vivo porcine eyes, where structural features including remnant vitreous humor, retina, and choroid can be clearly distinguished. Due to its imaging quality comparable to a commercial OCT system and compatibility with the current ophthalmic surgery standard, the probe can potentially serve as a better alternative to traditional visual inspection by white light illumination during vitreoretinal surgery (e.g., vitrectomy)

Planning progressive type-I interval censoring life tests with competing risks

[[abstract]]In this article, we investigate some reliability and quality problems when the competing risks data are progressive type-I interval censored with binomial removals. The failure times of the individual causes are assumed to be statistically independent and exponentially distributed with different parameters. We obtain the estimates of the unknown parameters through a maximum likelihood method, and also derive the Fisher's information matrix. The optimal lengths of the inspection intervals are determined under two different criteria. The reliability sampling plans are established under given producer's and customer's risks. A Monte Carlo simulation is conducted to evaluate the performance of the estimators, and also some numerical results are presented.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]電子

A General Light-Driven Organocatalytic Platform for the Activation of Inert Substrates

Due to their strong covalent bonds and low reduction potentials, activating inert substrates is challenging. Recent advances in photoredox catalysis offered a number of solutions, each of which useful for activating specific inert bonds. Developing a general catalytic platform that can consistently target a broad range of inert substrates would be synthetically useful. Herein, we report a readily available indole thiolate organocatalyst that, upon excitation with 405 nm light, acquires a strongly reducing power. This excited-state reactivity served to activate, by single-electron reduction, strong C-F, C-Cl, and C-O bonds in both aromatic and aliphatic substrates. This catalytic platform was versatile enough to promote the reduction of generally recalcitrant electron-rich substrates (E-red<-3.0 V vs SCE), including arenes that afforded 1,4-cyclohexadienes. The protocol was also useful for the borylation and phosphorylation of inert substrates with a high functional group tolerance. Mechanistic studies identified an excited-state thiolate anion as responsible of the highly reducing reactivity

Optimal Pilots for Anti-Eavesdropping Channel Estimation

Anti-eavesdropping channel estimation (ANECE) is a method that uses specially designed pilot signals to allow two or more full-duplex radio devices each with one or more antennas to estimate their channel state information (CSI) consistently and at the same time prevent eavesdropper (Eve) with any number of antennas from obtaining its CSI consistently. This paper presents optimal designs of the pilots for ANECE based on two criteria. The first is the mean squared error (MSE) of channel estimation for the users, and the second is the mutual information (MI) between the pilot-driven signals observed by the users. Closed-form optimal pilots are shown under the sum-MSE and sum-MI criteria subject to a symmetric and isotropic condition. Algorithms for computing the optimal pilots are shown for general cases. Fairness issues for three or more users are discussed. The performances of different designs are compared