Quality of experience (QoE) is the perceptual quality of service (QoS) from the users' perspective. For video service, the relationship between QoE and QoS (such as coding parameters and network ...statistics) is complicated because users' perceptual video quality is subjective and diversified in different environments. Traditionally, QoE is obtained from subjective test, where human viewers evaluate the quality of tested videos under a laboratory environment. To avoid high cost and offline nature of such tests, objective quality models are developed to predict QoE based on objective QoS parameters, but it is still an indirect way to estimate QoE. With the rising popularity of video streaming over the Internet, data-driven QoE analysis models have newly emerged due to availability of large-scale data. In this paper, we give a comprehensive survey of the evolution of video quality assessment methods, analyzing their characteristics, advantages, and drawbacks. We also introduce QoE-based video applications and, finally, identify the future research directions of QoE.
Human activities contribute greatly to heavy metal pollution in soils. Concentrations of 15 metal elements were detected in 105 soil samples collected from a typical rural-industrial town in southern ...Jiangsu, China. Among them, 7 heavy metals—lead, copper, zinc, arsenic, chromium, cadmium, and nickel—were considered in the health risk assessment for residents via soil inhalation, dermal contact, and/or direct/indirect ingestion. Their potential sources were quantitatively apportioned by positive matrix factorization using the data set of all metal elements, in combination with geostatistical analysis, land use investigation, and industrial composition analysis. Furthermore, the health risks imposed by sources of heavy metal in soil were estimated for the first time. The results indicated that Cr, Cu, Cd, Pb, Ni, and Co accumulated in the soil, attaining a mild pollution level. The total hazard index values were 3.62 and 6.11, and the total cancer risks were 9.78 × 10−4 and 4.03 × 10−4 for adults and children, respectively. That is, both non-carcinogenic and carcinogenic risks posed by soil metals were above acceptable levels. Cr and As require special attention because the health risks of Cr and As individually exceeded the acceptable levels. The ingestion of homegrown produce was predominantly responsible for the high risks. The potential sources were apportioned as: a) waste incineration and textile/dyeing industries (28.3%), b) natural sources (45.4%), c) traffic emissions (5.3%), and d) electroplating industries and livestock/poultry breeding (21.0%). Health risks of four sources accounted for 23.5%, 32.7%, 7.4%, and 36.4% of the total risk, respectively.
•Soil heavy metals caused unacceptable health risks, mainly through homegrown food.•Arsenic and chromium were the predominant hazardous elements.•Waste incineration, textile/dyeing industries were the main anthropogenic inputs.•Electroplating and livestock/poultry industries produced the highest health risks.
Music multimedia is one of the more popular types of digital music. This article is based on the hidden Markov model (HMM) and proposed this kind of music multimedia automatic classification method. ...The method not only analyzes the characteristics of traditional music in detail but also fully considers the important characteristics of other music. At the same time, it uses bagging to train two groups of HMMs and automatically classifies them to achieve a better classification effect. This paper optimizes the variable parameters from different aspects such as model structure, data form, and model change to obtain the optimal HMM parameter value. This method not only considers the prior knowledge of feature words, word frequency, and number of documents but also fuses the meaning of the feature words into the hidden Markov classification model. Finally, by testing the hidden Markov model used in this paper on the music multimedia data set, the experimental results show that the method in this paper can effectively perform automatic classification according to the melody characteristics of music multimedia.
Source-specific health risks of PM2.5-bound metals were analyzed for emission control by integrating source apportionment with health risk assessments of residents affected via inhalation pathways. A ...total of 218 daily PM2.5 samples were collected in 2016 in the central urban district of Beijing, China. Analyses showed that the mean annual concentrations of total heavy metals (THMs) and PM2.5 were 0.39 and 104.37 μg m−3, respectively. The heating season had significantly higher concentrations of THMs and PM2.5 (0.61, 134 μg m−3) than the non-heating season (0.27, 88.1 μg m−3) (p < 0.05). Among all metals, arsenic had the largest incremental cancer risk of 7.04 × 10−6. Six sources were identified by positive matrix factorization combined with conditional probability function and potential source contribution function analyses. The order of contribution to PM2.5-bound metal concentrations was resuspended dust (61.0%), traffic emission (16.3%), Cu-related industry (14.1%), coal combustion (3.7%), Cr-related industry (3.4%), and fuel oil combustion (1.6%). During the heating season, the contribution of coal combustion decreased slightly, which may have been due to the countermeasure of substituting coal for gas or electric heat in 2016. However, in terms of cancer risk contribution, coal combustion was the top contributor in both heating (3.5 × 10−6, 51.6%) and non-heating (2.7 × 10−6, 59.6%) seasons due to high attributable contents of the toxic metals, As, Cd and Pb. The Cr-related and Cu-related industries were the next controlled sources in the heating and non-heating seasons, respectively. Thus, these sources should receive priority in the development of control measures.
Display omitted
•Individual PM2.5-bound heavy metals have higher concentrations in heating season.•Arsenic had the largest cancer risk, exceeding the acceptable level (1 × 10−6).•Six identical sources with seasonal contribution order were found by PMF-CPF-PSCF.•Resuspended dust contributed the greatest mass concentration.•With the highest cancer risk, coal combustion should be the priority control objective.
Femtocell technology addresses the problem of poor indoor coverage, benefiting both wireless service provider (WSP) and end users. With the introduction of femtocell, the cross-tier interference ...between macro link and femto link becomes a major factor which greatly impacts the network performance. Different access control approaches, by generating different interference patterns, also severely affect the overall throughput of the network and need to be carefully investigated. Among all the access control mechanisms, hybrid access is the most promising one, which allows roaming unregistered users (referred to as macro users) to access the nearby femto base station (BS) while reserving certain resource for registered home users (referred to as femto users), improving overall network capacity. However, to successfully leverage hybrid access is challenging because the femto holders (FHs) are selfish, unwilling to share their femto facilities and spectrum resource with macro users without any incentive mechanism. In this paper, we propose a novel utility-aware refunding framework to motivate hybrid access in femtocell. Within the framework, both WSP and FHs are assumed to be selfish, and target at maximizing their own utilities. WSP provides certain refunding to motivate FHs to open their resource for macro users. FHs decide the resource allocation among femto and macro users according to the amount of refunding WSP offers. Under this framework, the optimal strategies of both WSP and FHs are analyzed by formulating the problem as a Stackelberg Game. A unique Nash Equilibrium is achieved and a hybrid access protocol is designed according to the analysis. Extensive simulations have been conducted and the results show that the utilities of both WSP and FHs are significantly improved exploiting the hybrid access mechanism.
Voluminous Mesozoic intra-continental granitic rocks occur in South China, which provide insights into the processes and associated P-T conditions of crustal anatexis and evolution in an ...intra-continental setting. Most granitic plutons contain multiple phase intrusions, commonly with an early-stage main-phase granite and a late-stage minor-phase highly fractionated granite, and the latter is generally thought to result from extreme differentiation of the main-phase granite. We challenge this model based on our case study on the Tianmenshan composite pluton that is composed of an early-stage biotite granite and a late-stage two-mica granite. Zircon U-Pb dating yields similar emplacement ages of 157.3 ± 3.1 Ma for the biotite granite and 158.5 ± 3.4 Ma for the two-mica granite. The two rock types are peraluminous with A/CNK = 1.07 to 1.17 and show comparable Nd isotopic compositions, with εNd(t) = −9.4 to −11.5 for the biotite granite and −10 to −11.2 for the two-mica granite. The two-mica granite is characterized by high silica (SiO2 = 75.2–77.5%), low abundances of Sr (2.3–42 ppm) and Ba (10–114 ppm), large negative Eu anomalies in the chondrite-normalized REE patterns and typical REE tetrad effect, which, along with its high Ga/Al ratios, Fe-index and F contents, suggesting its affinity to highly fractionated granite. Nevertheless, the petrographic observations, zircon REE concentrations and biotite compositions consistently demonstrate that the late-stage two-mica granite formed under more water-deficient and reduced conditions than the early-stage biotite granite. This, along with a modeling study of trace elements (Rb, Sr, Ba,Y and Nb) and the lack of continuum in terms of whole-rock chemistry and biotite compositions between the two rock units, suggests that the two-mica granite cannot be formed through differentiation of the main-phase biotite granite. We suggest that the parental magma to the late-stage two-mica granite could have been derived from partial melting of a granulitic residue after extraction of granitic melts to form the biotite granite from the Neoproterozoic metavolcano-sedimentary rocks, followed by a significant feldspar-dominated fractionation during magma ascent. This model may apply to most other composite granite plutons in South China, and is of significance to better understand the process of crustal anatexis and evolution in an intra-continental setting.
•Highly fractionated granite was not derived from differentiation of main-phase biotite granite.•Highly fractionated granite formed by melting of granulitic residue.•Enrichment of fluorine caused the geochemical features of highly fractionated granite.
PM2.5-bound toxic metals (TMs) are derived from various sources, and they can cause many adverse health effects on the human body. To effectively reduce the disease burden of TMs by controlling the ...relative sources, an integrated approach of quality-adjusted life years (QALYs) and source-apportionment (positive matrix factorization, PMF) was proposed and applied to some typical diseases induced by TMs in 2017 in Beijing. The estimation included two parts; first, the number of potentially affected people was calculated based on the source mass contribution from PMF and the inhalation unit risk of TMs; second, the QALYs lost per affected person was calculated based on the disease duration, expected years of life lost (EYLL) and quality of life (QoL) for both affected people and the general population. The results showed that QALYs lost per person for renal cancer (17.3 QALYs), pneumonia (14.4 QALYs), lung cancer (14.2 QALYs), skin cancer (12.7 QALYs) and diabetes mellitus (12.6 QALYs) were higher than those for other diseases. Combined with PMF, the source contributions to the overall burden of typical diseases from the TMs followed the order of coal combustion (50.2%) > vehicle emissions (24.4%) > fuel oil combustion (11.4%) > Cr-related industry (10.9%) > resuspended dust (3.0%). The rank was further compared with that assessed for noncancer and cancer risks, and we verified the reasonability of the QALYs method. For seasonal contributions to coal combustion, winter and spring had the highest contributions, which coincided with the fact that coal was the main fuel for heating in Beijing. The QALYs lost attributed to TMs for coal combustion decreased by 49.1% from 2016 to 2017, which may indicate an effective policy associated with coal control. Overall, the integrated approach was successfully employed for estimating the disease burden induced by TMs from each source and was an effective solution to identify the control rank of sources for TM reduction.
Display omitted
•QALYs and PMF were integrated to quantify the source-attributed disease burden for TMs.•A model of calculating the QALYs lost per person for typical diseases was built.•The ranks of source-attributed QALYs lost from PM2.5-bound TMs were clarified.•Coal burning contribution to the QALYs lost to TMs was the highest but sharply decreased.•More pollutants/toxic effects should be included to determine priority source control.
Auction is an effective way to allocate goods or services to bidders who value them the most. The rapid growth of e-auctions facilitates online transactions but poses new and distinctive challenges. ...It is difficult to establish trust among sellers, buyers, and auctioneers without centralized auction websites or platforms (the auctioneer) which collect bids and derive the auction results. However, these third parties may be untrustworthy, and malicious sellers or buyers may refuse to deliver the goods or payment according to the protocol. Moreover, the open and anonymous online environment may stimulate auction participants to form collusion coalitions to rig the auction and reap unfair profit. Many auction designs have been proposed to address these concerns, but they fall short of simultaneously achieving decentralization (i.e., held without a trusted third utility), strong consensus (i.e., the establishment of trust), collusion resistance, and practical implementation. We present CReam, the first decentralized collusion-resistant e-auction system that is implemented with smart contract on the blockchain. With the carefully designed smart auction contract, mutually distrustful and rational sellers and buyers are stimulated to operate properly, hence transact safely without trusted third parties. The auction mechanism in the smart contract can effectively prevent bidder collusion and realize economic robustness, i.e., truthfulness. We implement a fully functional CReam on the Ethereum network. Extensive experimental results confirm that CReam can greatly reduce the probability of collusion and achieve an approximate optimal revenue at a low cost of contract execution.
The femtocell technique can address the poor in-building coverage problem and increase net work capacity cost efficiently. At present, some wireless service providers have launched their femtocell ...services, although there are still plenty of challenges unsettled. In this article we discuss the business mode in macro-femto heterogeneous networks. We propose three frameworks according to the deployment types of femtocells, which are joint deployment, WSP deployment, and user deployment frameworks. Their unique characteristics, corresponding challenges, and potential solutions are further investigated to provide deeper insight systematically. We also present two schemes for WSP revenue maximization under the WSP deployment framework. The first scheme jointly handles the interference and users' demand satisfaction via cross-tier channel allocation, and the second scheme further considers the optimal pricing selection for accessing different networks.
We carried out combined Nd and Li isotopic studies on the Neoproterozoic biotite granites, late Mesozoic evolved two-mica/muscovite granites and associated the Shuangqiaoshan Group metapelites from ...the Jiangnan Orogen (South China), which, along with petrological and geochemical data, were used to constrain the lithium isotopic behavior during partial melting of metapelites, the origin of the REE tetrad effect in evolved granites, and implications for related rare-metal mineralization. The Neoproterozoic biotite granites show features typical of S-types (e.g., high A/CNK ratios), and have εNd = −6.9 to −10 and δ7Li = −2.2–−4‰, comparable to the Shuangqiaoshan Group metapelites (with εNd = −6 to −11 and δ7Li = −2–−3.7‰, respectively), suggesting that the biotite granites were derived from melting of the metapelites and the Li isotopic fractionation during the melting process appears negligible. The two late Mesozoic Shimensi and Zengjialong granites occur as small stocks, showing high silica, peraluminous, low CaO and Sr contents, variably enrichment in volatiles (F, B), and are accompanied by W-Cu and Sn mineralization. The Shimensi granites have εNd(t) values of −7.0–−8.6 and δ7Li = −2.7‰–−3.9‰, similar to the Shuangqiaoshan Group metapelites, whereas the Zengjialong granites have relatively high εNd(t) values (−5.1–−7.3) and heavy Li isotopic features (mostly δ7Li = −0.18‰–+1.53‰), and particularly, REE tetrad effect is seen in the latter. We argue that the late Mesozoic evolved granites formed as a result of re-melting of the granulitic residues left in the lower crust after extraction of the Neoproterozoic biotite granites from the metapelites. Such re-melting of the residues was triggered by underplating of basaltic magma, with more mantle input (and F, B as well) in the source of the Zengjialong granites. The elevated δ7Li values of the Zengjialong granites were probably caused by intense interaction between melt and external fluids during magma emplacement, which, in turn, resulted in the formation of the REE tetrad effect in the granites. Isotopic modeling suggests that fluid exsolution from evolved granites is minor, and is less likely to have been responsible for the extensive rare-metal mineralization as traditionally thought.
Display omitted
•REE tetrad effect of granite is formed by interaction of melt with external fluid.•Elevated δ7Li of granite is linked with interaction with external fluid.•Rare-metal ore is not attributable to fluid exsolution from granite.
PDF
