Joint Data compression and Computation offloading in Hierarchical Fog-Cloud Systems

Data compression has the potential to significantly improve the computation offloading performance in hierarchical fog-cloud systems. However, it remains unknown how to optimally determine the compression ratio jointly with the computation offloading decisions and the resource allocation. This joint optimization problem is studied in the current paper where we aim to minimize the maximum weighted energy and service delay cost (WEDC) of all users. First, we consider a scenario where data compression is performed only at the mobile users. We prove that the optimal offloading decisions have a threshold structure. Moreover, a novel three-step approach employing convexification techniques is developed to optimize the compression ratios and the resource allocation. Then, we address the more general design where data compression is performed at both the mobile users and the fog server. We propose three efficient algorithms to overcome the strong coupling between the offloading decisions and resource allocation. We show that the proposed optimal algorithm for data compression at only the mobile users can reduce the WEDC by a few hundred percent compared to computation offloading strategies that do not leverage data compression or use sub-optimal optimization approaches. Besides, the proposed algorithms for additional data compression at the fog server can further reduce the WEDC

Exploring EFL teachers’ use of written instructions and their subsequent verbal instructions for the same tasks

publishedVersio

Effect of land-use changes resulting from shrimp farming on acid sulfate soils in the Can Gio coastal wetland area (Vietnam)

Acid sulfate soils in coastal wetland areas are particularly vulnerable to land-use changes. We identifid the potential impacts of land-use changes in the Can Gio coastal wetland area in Vietnam due to the reclamation of acid sulfate soils from shrimp farms. Our study applied the support of vector machine algorithm in ENVI software to observe land-use changes from 1995 to 2015, using Landsat Thematic Mapper and Operational Land Imager data. We classifid the land use of the study area into four major classes including vegetation, bare land, dedicated land and aquaculture land. Our study successfully met the overall classifiation accuracy requirement above 95% and kappa statistics above 0.95. Between 1995 and 2006, about 2,938.05 ha of bare land and 1,464.66 ha of vegetation (mangrove forest) were converted to aquaculture land. In contrast, between 2006 and 2015, 2,423.88 ha of aquaculture land converted back to bare land, mainly related to the abandonment of shrimp ponds due to crop failure and disease. The disturbance of acid sulfate soils through initial soil reclamation and subsequent fallowing is considered a key reason for hastening and extending soil acidifiation in the study area. We collected 144 topsoil samples from 17 fallowed ponds in two batches, and 142 of these were acidic: 128 samples were extremely and strongly acidic (pH < 5.5), 14 samples were moderately and slightly acid (pH between 5.5 and 6.5), and only two samples were neutral (pH over 6.5)

Cost of Debt and Political Connection of Firms in Vietnam

The purpose of the paper is to present a proposed study on the relationship between the interest rate charged on debt and political connection of firms in Vietnam. Data on cost of debt and political connection from 600 Vietnamese public firms over a period from 2016 to 2018 is gathered to examine the research hypotheses. The present study extends the previous research that finds politically connected firms (PCON) are generally considered as higher risk than that of non-PCON firms by both the market and audit firms in emerging economy, by providing the evidence in Vietnam that lenders also view these firms as higher risk

Computation Offloading and Resource Allocation for Backhaul Limited Cooperative MEC Systems

In this paper, we jointly optimize computation offloading and resource allocation to minimize the weighted sum of energy consumption of all mobile users in a backhaul limited cooperative MEC system with multiple fog servers. Considering the partial offloading strategy and TDMA transmission at each base station, the underlying optimization problem with constraints on maximum task latency and limited computation resource at mobile users and fog servers is non-convex. We propose to convexify the problem exploiting the relationship among some optimization variables from which an optimal algorithm is proposed to solve the resulting problem. We then present numerical results to demonstrate the significant gains of our proposed design compared to conventional designs without exploiting cooperation among fog servers and a greedy algorithm

Systematical calculation of alpha decay half-lives with a generalized liquid drop model

International audienceA systematic calculation of α decay half-lives is presented for even-even nuclei between Te and Z=118 isotopes. The potential energy governing α decay has been determined within a liquid drop model including proximity effects between the α particle and the daughter nucleus and taking into account the experimental Q value. The α decay half-lives have been deduced from the WKB barrier penetration probability. The α decay half-lives obtained agree reasonably well with the experimental data

FACTORS AFFECTING MOTIVATION OF ENGLISH-MAJORED STUDENTS TOWARDS LEARNING ENGLISH AT A UNIVERSITY IN THE MEKONG DELTA, VIETNAM

It could be broadly accepted that motivation plays its fundamental role as one of the most important elements in foreign language learning. The present research investigated factors affecting motivation in learning English of freshmen at Tay Do University. The participants were 84 freshmen studying in Faculty of Linguistics and Literature. In the study process, these participants were given questionnaires which consisted of several statements related to the mentioned factors and the interview to get information. The collected data from the two instruments mentioned above were all analyzed afterward. The current study showed that there were elements that motivate freshmen towards English learning. Parental, environmental, teacher’s and intrinsic (personal) factors were examined. It is hoped that this research can be helpful for not only students but also teachers in learning and teaching English. Article visualizations

Fetus Trafficking in Viet Nam – The New Criminal Method of Human Trafficking

When it comes to basic rights of the fetus, including the right to life, theoretical studies around the world on human rights of the fetus still have not reached an agreement on approaches and explanation. Criminal law at the international and national levels still leaves the possibility of protecting the unborn child. Viet Nam’s criminal law is no exception to this trend. In addition, Viet Nam is currently facing human trafficking with new methods and tricks. Children are bought and paid for while still in the womb, then born abroad and given to traffickers. Children are only protected by criminal law for human trafficking if they are born, alive, and detected by the authorities. While the act of trafficking in fetuses is often easily detected by the authorities right from the stage of purchasing and paying, it is not feasible to prosecute this act for human trafficking under the criminal law of Viet Nam. This reduces the criminal law’s ability to suppress crime, at the same time, leaves many fetuses unprotected. Should criminal law be left outside the legal mechanism to protect children while in the fetal stage? This article suggests considering fetus trafficking as a form of human trafficking and to criminalize fetus trafficking. Criminal law should recognize fetus trafficking as a sign of crime or an early stage in the criminal process of human trafficking, because children need special care and protection, including appropriate legal protection before and after birth, due to their physical and mental immaturity

Electrodeposition from a Graphene Bath: A Sustainable Copper Composite Alloy in a Graphene Matrix

The leaching effect of metals has led to the introduction of government regulations for the safety of the environment and humans. This has led to the search for new alloys with long-lasting sustainability. Herein, we wish to report a new brass alloy containing carbon with a remarkable sustainability produced by electrodeposition from a graphene quantum dots bath. The electrochemical measurements were carried out using cyclic voltammetry, potentiodynamic analysis, and Tafel measurements, and the deposits were characterized by X-ray fluorescence spectroscopy (XRF), Raman imaging, X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) to understand the surface morphology and elemental compositions. The current–time transients in the potential-step electrolysis were used to investigate the nucleation and growth mechanism. The smooth and compact deposit obtained at −0.60 V showed a composition of Cu = 24.33 wt %; Zn = 0.089 wt %; and C = 75.57 wt %. The SEM and energy dispersion X-ray analysis revealed a surface morphology with a uniform distribution of the particles and the presence of Cu, Zn, and C. The corrosion density of the material is very much lower than that of conventional brass, suggesting a higher sustainabilit

Dual-Stub Ka-Band Vivaldi Antenna with Integrated Bandpass Filter

A dual-stub coplanar Vivaldi antenna with a parasitic element is presented. The dual-stub is coupled between the parasitic element and two tapered slots. The parasitic element shape and size is optimised. The use of slits on the outer edge of the ground plane is shown to provide control of beamwidth and maximum gain. A bandpass filter is used for performance control and sub-harmonic suppression