0000000000374027
AUTHOR
Li Han
showing 7 related works from this author
Ultrasensitive and highly specific detection of iodine ions using zirconium (IV)-enhanced oxidation
2022
Nuclear energy has significantly promoted the development of human society. However, nuclear pollution caused by nuclear accidents can lead to significant hazards to the environment and human health. As a major radioactive product, radioactive iodine (mainly existing as I−) detection has attracted significant attentions. In this study, zirconium(IV) is used to enhance the oxidation of environmental I− to form I2. Subsequently, the generated I2 oxidizes the chemical chromogenic substrate 3,3′,5,5′-tetramethylbenzidine, which is used for I− detection and realizes an ultralow limit of detection (LoD) of 0.176 nM. The LoD of our method, to the best of our knowledge, is the lowest among those of…
Segmented Thermoelectric Oxide-Based Module for High-Temperature Waste Heat Harvesting
2015
We report a high-performance thermoelectric (TE) oxide-based module using the segmentation of half-Heusler Ti_(0.3)Zr_(0.35)Hf_(0.35)CoSb_(0.8)Sn_(0.2) and misfit-layered cobaltite Ca_3Co_4O_(9+δ) as the p-leg and 2 % Al-doped ZnO as the n-leg. The maximum output power of a 4-couple segmented module at ΔT=700 K attains a value of approximately 6.5 kW m^(−2), which is three times higher than that of the best reported non-segmented oxide module. The TE properties of individual legs, as well as the interfacial contact resistances, were characterized as a function of temperature. Numerical modeling was used to predict the efficiency and to evaluate the influence of the electrical and thermal lo…
Development of silicon pad detectors and readout electronics for a Compton camera
2003
Abstract Applications in nuclear medicine and bio-medical engineering may profit using a Compton camera for imaging distributions of radio-isotope labelled tracers in organs and tissues. These applications require detection of photons using thick position-sensitive silicon sensors with the highest possible energy and good spatial resolution. In this paper, research and development on silicon pad sensors and associated readout electronics for a Compton camera are presented. First results with low-noise, self-triggering VATAGP ASIC's are reported. The measured energy resolution was 1.1 keV FWHM at room temperature for the 241 Am photo-peak at 59.5 keV .
First coincidences in pre-clinical Compton camera prototype for medical imaging
2003
Abstract Compton collimated imaging may improve the detection of gamma rays emitted by radioisotopes used in single photon emission computed tomography (SPECT). We present a crude prototype consisting of a single 500 μm thick, 256 pad silicon detector with pad size of 1.4×1.4 mm 2 , combined with a 15×15×1 cm 3 NaI scintillator crystal coupled to a set of 20 photo multipliers. Emphasis is placed on the performance of the silicon detector and the associated read-out electronics, which has so far proved to be the most challenging part of the set-up. Results were obtained using the VATAGP3, 128 channel low-noise self-triggering ASIC as the silicon detector's front-end. The noise distribution (…
A Generic Approach to Scheduling and Checkpointing Workflows
2018
This work deals with scheduling and checkpointing strategies to execute scientific workflows on failure-prone large-scale platforms. To the best of our knowledge, this work is the first to target fail-stop errors for arbitrary workflows. Most previous work addresses soft errors, which corrupt the task being executed by a processor but do not cause the entire memory of that processor to be lost, contrarily to fail-stop errors. We revisit classical mapping heuristics such as HEFT and MinMin and complement them with several checkpointing strategies. The objective is to derive an efficient trade-off between checkpointing every task (CkptAll), which is an overkill when failures are rare events, …
Checkpointing Workflows for Fail-Stop Errors
2017
International audience; We consider the problem of orchestrating the exe- cution of workflow applications structured as Directed Acyclic Graphs (DAGs) on parallel computing platforms that are subject to fail-stop failures. The objective is to minimize expected overall execution time, or makespan. A solution to this problem consists of a schedule of the workflow tasks on the available processors and of a decision of which application data to checkpoint to stable storage, so as to mitigate the impact of processor failures. For general DAGs this problem is hopelessly intractable. In fact, given a solution, computing its expected makespan is still a difficult problem. To address this challenge,…
High performance p-type segmented leg of misfit-layered cobaltite and half-Heusler alloy
2015
In this study, a segmented p-type leg of doped misfit-layered cobaltite Ca_(2.8)Lu_(0.15)Ag_(0.05)Co_4O_(9+δ) and half-Heusler Ti_(0.3)Zr_(0.35)Hf_(0.35)CoSb_(0.8)Sn_(0.2) alloy was fabricated and characterized. The thermoelectric properties of single components, segmented leg, and the electrical contact resistance of the joint part were measured as a function of temperature. The output power generation characteristics of segmented legs were characterized in air under various temperature gradients, ΔT, with the hot side temperature up to 1153 K. At ΔT ≈ 756 K, the maximum conversion efficiency reached a value of ∼5%, which is about 65% of that expected from the materials without parasitic l…