212 research outputs found

    The Impact of Increased Import Competition from the People’s Republic of China on Income Inequality and Household Welfare in Viet Nam

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    This paper examines the surge of imports from the PRC to Viet Nam from 2000 to 2014 in order to evaluate the effects of increased exposure to trade with the PRC on income inequality and household welfare in Viet Nam. Using household level data from the Viet Nam Household Living Standard Survey and combining it with measures of trade exposure, we find that increased imports led to a fall in inequality at the provincial and district level. We distinguish between intermediate and final goods and find similar results. In order to better understand the relative gains and losses across income groups, we apply a quantile regression approach. Our results indicate that increased imports were more often positively correlated with household income for households located in the lower quantiles. In contrast, for households in the upper quantiles the correlation is either negative or less pronounced

    Compositional Verification of Heap-Manipulating Programs through Property-Guided Learning

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    Analyzing and verifying heap-manipulating programs automatically is challenging. A key for fighting the complexity is to develop compositional methods. For instance, many existing verifiers for heap-manipulating programs require user-provided specification for each function in the program in order to decompose the verification problem. The requirement, however, often hinders the users from applying such tools. To overcome the issue, we propose to automatically learn heap-related program invariants in a property-guided way for each function call. The invariants are learned based on the memory graphs observed during test execution and improved through memory graph mutation. We implemented a prototype of our approach and integrated it with two existing program verifiers. The experimental results show that our approach enhances existing verifiers effectively in automatically verifying complex heap-manipulating programs with multiple function calls

    S2TD: a Separation Logic Verifier that Supports Reasoning of the Absence and Presence of Bugs

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    Heap-manipulating programs are known to be challenging to reason about. We present a novel verifier for heap-manipulating programs called S2TD, which encodes programs systematically in the form of Constrained Horn Clauses (CHC) using a novel extension of separation logic (SL) with recursive predicates and dangling predicates. S2TD actively explores cyclic proofs to address the path explosion problem. S2TD differentiates itself from existing CHC-based verifiers by focusing on heap-manipulating programs and employing cyclic proof to efficiently verify or falsify them with counterexamples. Compared with existing SL-based verifiers, S2TD precisely specifies the heaps of de-allocated pointers to avoid false positives in reasoning about the presence of bugs. S2TD has been evaluated using a comprehensive set of benchmark programs from the SV-COMP repository. The results show that S2TD is more effective than state-of-art program verifiers and is more efficient than most of them.Comment: 24 page

    Concolic Testing Heap-Manipulating Programs

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    Concolic testing is a test generation technique which works effectively by integrating random testing generation and symbolic execution. Existing concolic testing engines focus on numeric programs. Heap-manipulating programs make extensive use of complex heap objects like trees and lists. Testing such programs is challenging due to multiple reasons. Firstly, test inputs for such program are required to satisfy non-trivial constraints which must be specified precisely. Secondly, precisely encoding and solving path conditions in such programs are challenging and often expensive. In this work, we propose the first concolic testing engine called CSF for heap-manipulating programs based on separation logic. CSF effectively combines specification-based testing and concolic execution for test input generation. It is evaluated on a set of challenging heap-manipulating programs. The results show that CSF generates valid test inputs with high coverage efficiently. Furthermore, we show that CSF can be potentially used in combination with precondition inference tools to reduce the user effort

    Criblage virtuel sur grille de composés isolés au Vietnam

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    Criblage virtuel sur grille de composés isolés au Vietna

    Intensified distillation-based separation processes: Recent developments and perspective

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    Greater sustainability can be achieved by decreasing the production costs, energy consumption, equipment size, and environmental impact as well as improvement of the raw material yields, remote control, and process flexibility. Process intensification (PI) as the main route for improving the process performance is used widely in heat transfer, reactions, separation, and mixing, which results in plant compactness, cleanliness, and energy efficiency. Some of the main intensified separation processes and improvement mechanisms are reviewed briefly with the main focus on the PI of distillation processes, which are the most important separation methods. In addition to these technologies, the potential and reliability of reactive separation processes are addressed briefly, which will enable higher efficiency and capacity

    HybridMingler: Towards Mixed-Reality Support for Mingling at Hybrid Conferences

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    Mingling, the activity of ad-hoc, private, opportunistic conversations ahead of, during, or after breaks, is an important socializing activity for attendees at scheduled events, such as in-person conferences. The Covid-19 pandemic had a dramatic impact on the way conferences are organized, so that most of them now take place in a hybrid mode where people can either attend on-site or remotely. While on-site attendees can resume in-person mingling, hybrid modes make it challenging for remote attendees to mingle with on-site peers. In addressing this problem, we propose a collaborative mixed-reality (MR) concept, including a prototype, called HybridMingler. This is a distributed MR system supporting ambient awareness and allowing both on-site and remote conference attendees to virtually mingle. HybridMingler aims to provide both on-site and remote attendees with a spatial sense of co-location in the very same venue location, thus ultimately improving perceived presence

    HYDROGEN-PLASMA-TREATED NANO TIO2 FOR PHOTOCATALYTIC OXIDATION OF VOCS IN AIR STREAM

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    Unlike water treatment processes, the photocatalytic oxidation of VOCs in air stream exhibits many challenges. This study will develop the hydrogen-plasma-treated TiO2 with improvement in photocatalytic activity. The hydrogen-plasma-treatment was carried out in the non-thermal atmospheric pressure reactor at room temperature or above. The catalysts were prepared and analyzed by advanced techniques such as X-ray diffraction (XRD), scanning electro-microscopy (SEM) and transmission electro-microscopy (TEM). The photocatalytic activity of the catalyst has been investigated under UV light with various reaction conditions such as different initial toluene/formaldehyde concentrations and water content. Significantly, the conversion of toluene by a plasma-treated sample was 1.5 times higher than the bare TiO2 in a similar reaction condition

    TECHNICAL ASSESSMENT OF GAMMA-AMINO BUTYRIC ACID (GABA) PRODUCTION FROM RICE BRAN

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    This research focused on technical assessment of GABA production from rice bran through fermentation by Lactobacillus brevis. Influence of operating pressure on separation of GABA by nanofiltration membrane was investigated and 4 bar was suitable for the nanofiltration process. The purification of GABA by nanofiltration with constant feed volume was carried out and purity of GABA reached 4.8 folds, compared to feed, at 5 volumes of added water. At 40 of concentration factor in concentration of GABA solution by nanofiltration with full recycle of retentate, content of GABA reached 49.8 g/L. The production of GABA from defatted rice bran at pilot scale was carried out at 1,000 L/batch (equal to 200 kg of rice bran) of fermentation. Estimation of mass balance showed that, with 200 kg of defatted rice bran, 7.0 kg of GABA powder was obtained. Results indicated that, it is potential to produce GABA from rice bran through the fermentation by Lactobacillus brevis

    First report and new molecular and morphological characterizations of root-knot nematode, Meloidogyne javanica, infecting ginger and long coriander in Vietnam

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    Ginger (Zingiber offcinale Roscoe) and long coriander (Eryngium foetidum L.) are commonly grown and used as important spices and medicinal plants in Vietnam. Our study recovered for the frst time one of the most damaging tropical root-knot nematodes, Meloidogyne javanica, associated with these plants in the Western Highlands of Vietnam. In this study, M. javanica was characterized based on morphology and molecular characterization of D2-D3 fragment of 28S rRNA, ITS, and Nad5 mtDNA regions. The identifcation of this species was done based on a combination of morphology, multiplexPCR with specifc primer, network haplotype analysis, and PPNID program
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