| 41. |
- Cao, Zhiguo, et al.
(författare)
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Economic status as a determinant of national PCDD/PCDF releases and implications for PCDD/PCDF reduction
- 2013
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 91:3, s. 328-335
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Tidskriftsartikel (refereegranskat)abstract
- The annual releases of polychlorinated dibenzo-para-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) from 68 countries/regions were investigated by correlating quantitative emissions with economic status of the nations. The national dioxin/furan inventories were developed using the PCDD/PCDF Standardized Toolldt, which presents the quantitative releases from ten major source groups to five release vectors. The correlation between intensity of PCDDIPCDF release and economic status was discussed and the influence of economic status on composition of five release vectors and ten source groups was studied. As PCDD/PCDF are mainly released from human activities to environmental matrices, release per person (RpP) and release per unit area (RpA) are defined to reflect release burden (Donor) and contamination burden (Receptor), respectively. Based on these two concepts, International PCDD/PCDF Reduction Burden is characterized by burden quotient (BQ) and a calculation model is established. The numbers of countries/regions with high, moderate and low International PCDD/PCDF Reduction Burden were 19,31 and 18, respectively. The information in this paper can be used for politicians to develop legislations to improve International PCDD/PCDF Reduction.
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| 42. |
- Cao, Zhi-Guo, et al.
(författare)
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Particle size : A missing factor in risk assessment of human exposure to toxic chemicals in settled indoor dust
- 2012
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 49, s. 24-30
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Tidskriftsartikel (refereegranskat)abstract
- For researches on toxic chemicals in settled indoor dust, selection of dust fraction is a critical influencing factor to the accuracy of human exposure risk assessment results. However, analysis of the selection of dust fraction in recent studies revealed that there is no consensus. This study classified and presented researches on distribution of toxic chemicals according to dust particle size and on relationship between dust particle size and human exposure possibility. According to the literature, beyond the fact that there were no consistent conclusions on particle size distribution of adherent fraction, dust with particle size less than 100 mu m should be paid more attention and that larger than 250 mu m is neither adherent nor proper for human exposure risk assessment. Calculation results based on literature data show that with different selections of dust fractions, analytical results of toxic chemicals would vary up to 10-fold, which means that selecting dust fractions arbitrarily will lead to large errors in risk assessment of human exposure to toxic chemicals in settled dust. Taking into account the influence of dust particle size on risk assessment of human exposure to toxic chemicals, a new methodology for risk assessment of human exposure to toxic chemicals in settled indoor dust is proposed and human exposure parameter systems to settled indoor dust are advised to be established at national and regional scales all over the world.
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| 43. |
- Chen, Bin, et al.
(författare)
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Full-colour luminescent compounds based on anthracene and 2,2 '-dipyridylamine
- 2013
-
Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 1:44, s. 7409-7417
-
Tidskriftsartikel (refereegranskat)abstract
- Starting from two simple units of anthracene and 2,2'-dipyridylamine, a series of new luminescent compounds 1-8 were designed and synthesized by a combined strategy of changing the connection mode between the two units, extending the conjugation size, and introducing an additional electron donor. Photophysical properties of 1-8 were investigated and discussed on the basis of solvatochromic behaviour, theoretical calculations, crystal structure, and optimized structures. Interestingly, the emission wavelengths of these compounds could be successfully tuned from violet to red both in solutions and the solid-state, and prominent positive solvatochromism was observed for the compounds with a D-p-A framework. Consider compound 7 as an example, it shows peaks at 526 nm and 627 nm in cyclohexane and DMSO, respectively. Meanwhile, the quantum yield was decreased from 0.80 in cyclohexane to 0.12 in DMSO. The introduction of bulky groups was demonstrated to be effective for suppressing the aggregation effect and thus improving the solid state emission quantum yield. These results indicate that the combined structure modulation strategy offers a powerful tool for tuning the emission behaviour. To demonstrate the possibility of practical applications, 2 was employed as the emitting material for the fabrication of deep-blue organic light-emitting diodes (OLEDs), which showed a maximum external quantum efficiency of 2.2%. The CIE coordinates of (0.15, 0.08) are indicative of excellent blue color purity.
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| 44. |
- Chen, Cheng, et al.
(författare)
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A novel multi-source data fusion method based on Bayesian inference for accurate estimation of chlorophyll-a concentration over eutrophic lakes
- 2021
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Ingår i: Environmental Modelling and Software. - : Elsevier. - 1364-8152. ; 141
-
Tidskriftsartikel (refereegranskat)abstract
- A novel multi-source data fusion method based on Bayesian inference (BIF) was proposed in this study to blend the advantages of in-situ observations and remote sensing estimations for obtaining accurate chlorophyll-a (Chla) concentration in Lake Taihu (China). Two error models (additive and multiplicative) were adopted to construct the likelihood function in BIF; the BIF method was also compared with three commonly used data fusion algorithms, including linear and nonlinear regression data fusion (LRF and NLRF) and cumulative distribution function matching data fusion (CDFF). The results showed the multiplicative error model had small normalized residual errors and was a more suitable choice. The BIF method largely outperformed the data fusion algorithms of CDFF, NLRF and LRF, with the largest correlation coefficients and smallest root mean square error. Moreover, the BIF results can capture the high Chla concentrations in the northwest and the low Chla concentrations in the east of Lake Taihu.
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| 45. |
- Chen, Gang, et al.
(författare)
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BCJ numerators from differential operator of multidimensional residue
- 2020
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:1
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Tidskriftsartikel (refereegranskat)abstract
- In previous works, we devised a differential operator for evaluating typical integrals appearing in the Cachazo-He-Yuan (CHY) forms and in this paper we further streamline this method. We observe that at tree level, the number of free parameters controlling the differential operator depends solely on the number of external lines, after solving the constraints arising from the scattering equations. This allows us to construct a reduction matrix that relates the parameters of a higher-order differential operator to those of a lower-order one. The reduction matrix is theory-independent and can be obtained by solving a set of explicitly given linear conditions. The repeated application of such reduction matrices eventually transforms a given tree-level CHY-like integral to a prepared form. We also provide analytic expressions for the parameters associated with any such prepared form at tree level. We finally give a compact expression for the multidimensional residue for any CHY-like integral in terms of the reduction matrices. We adopt a dual basis projector which leads to the CHY-like representation for the non-local Bern-Carrasco-Johansson (BCJ) numerators at tree level in Yang-Mills theory. These BCJ numerators are efficiently computed by the improved method involving the reduction matrix.
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| 46. |
- Chen, Gang, et al.
(författare)
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EDF-VD Scheduling of Flexible Mixed-Criticality System With Multiple-Shot Transitions
- 2018
-
Ingår i: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems. - 0278-0070 .- 1937-4151. ; 37:11, s. 2393-2403
-
Tidskriftsartikel (refereegranskat)abstract
- The existing mixed-criticality (MC) real-time task models assume that once any high-criticality task overruns, all high-criticality jobs execute up to their most pessimistic WCET estimations simultaneously in a one-shot manner. This is very pessimistic in the sense of unnecessary resource overbooking. In this paper, we propose a more generalized mixed-critical real-time task model, called flexible MC model with multiple-shot transitions (FMC-MST), to address this problem. In FMC-MST, high-criticality tasks can transit multiple intermediate levels to handle less pessimistic overruns independently and to nonuni-formly scale the deadline on each level. We develop a run-time schedulability analysis for FMC-MST under EDF-VD scheduling, in which a better tradeoff between the penalties of low-criticality tasks and the overruns of high-criticality tasks is achieved to improve the service quality of low-criticality tasks. We also develop a resource optimization technique to find resource-efficient level-insertion configurations for FMC-MST task systems under MC timing constraints. Experiments demonstrate the effectiveness of FMC-MST compared with the state-of-the-art techniques.
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| 47. |
- Chen, Gang, et al.
(författare)
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Fault-tolerant real-time tasks scheduling with dynamic fault handling
- 2020
-
Ingår i: Journal of systems architecture. - : ELSEVIER. - 1383-7621 .- 1873-6165. ; 102
-
Tidskriftsartikel (refereegranskat)abstract
- Predictable performance when coping with transient failures is of paramount importance in safety-critical real-time systems. Various software fault-tolerant techniques are employed towards this goal among which check-pointing is a relatively cost-effective scheme. In this paper, we propose an efficient fault-tolerant scheduling framework with run-time fault handling protocol, where criticality levels can be adaptively inserted for fault handling according to run-time fault workload. In contrast to prior works which apply with task re-execution strategy, the proposed framework adaptively determines on-demand re-executions only on the faulty checkpoint segments, rather than on the whole job. Towards this, a unified overrun handling protocol is developed to handle fault recovery adaptively to avoid over-provisioning of resources. In addition, we develop an off-line schedulability analysis technique for the proposed scheduling algorithm. The simulation results show that our fault-tolerant scheduling framework can bring up to 81% improvement in supporting low-criticality service without sacrifice in the MC-schedulability compared with the existing techniques.
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| 48. |
- Chen, Gang, et al.
(författare)
-
Next-to-MHV Yang-Mills kinematic algebra
- 2021
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :10
-
Tidskriftsartikel (refereegranskat)abstract
- Kinematic numerators of Yang-Mills scattering amplitudes possess a rich Lie algebraic structure that suggest the existence of a hidden infinite-dimensional kinematic algebra. Explicitly realizing such a kinematic algebra is a longstanding open problem that only has had partial success for simple helicity sectors. In past work, we introduced a framework using tensor currents and fusion rules to generate BCJ numerators of a special subsector of NMHV amplitudes in Yang-Mills theory. Here we enlarge the scope and explicitly realize a kinematic algebra for all NMHV amplitudes. Master numerators are obtained directly from the algebraic rules and through commutators and kinematic Jacobi identities other numerators can be generated. Inspecting the output of the algebra, we conjecture a closed-form expression for the master BCJ numerator up to any multiplicity. We also introduce a new method, based on group algebra of the permutation group, to solve for the generalized gauge freedom of BCJ numerators. It uses the recently introduced binary BCJ relations to provide a complete set of NMHV kinematic numerators that consist of pure gauge.
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| 49. |
- Chen, Gang, et al.
(författare)
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On the kinematic algebra for BCJ numerators beyond the MHV sector
- 2019
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :11
-
Tidskriftsartikel (refereegranskat)abstract
- The duality between color and kinematics present in scattering amplitudes of Yang-Mills theory strongly suggests the existence of a hidden kinematic Lie algebra that controls the gauge theory. While associated BCJ numerators are known on closed forms to any multiplicity at tree level, the kinematic algebra has only been partially explored for the simplest of four-dimensional amplitudes: up to the MHV sector. In this paper we introduce a framework that allows us to characterize the algebra beyond the MHV sector. This allows us to both constrain some of the ambiguities of the kinematic algebra, and better control the generalized gauge freedom that is associated with the BCJ numerators. Specifically, in this paper, we work in dimension-agnostic notation and determine the kinematic algebra valid up to certain ? ((epsilon i .epsilon j )(2)) terms that in four dimensions compute the next-to-MHV sector involving two scalars. The kinematic algebra in this sector is simple, given that we introduce tensor currents that generalize standard Yang-Mills vector currents. These tensor currents control the generalized gauge freedom, allowing us to generate multiple different versions of BCJ numerators from the same kinematic algebra. The framework should generalize to other sectors in Yang-Mills theory.
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| 50. |
- Chen, Gang, et al.
(författare)
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Utilization-Based Scheduling of Flexible Mixed-Criticality Real-Time Tasks
- 2018
-
Ingår i: IEEE Transactions on Computers. - : IEEE COMPUTER SOC. - 0018-9340 .- 1557-9956. ; 67:4, s. 543-558
-
Tidskriftsartikel (refereegranskat)abstract
- Mixed-criticality models are an emerging paradigm for the design of real-time systems because of their significantly improved resource efficiency. However, formal mixed-criticality models have traditionally been characterized by two impractical assumptions: once any high-criticality task overruns, all low-criticality tasks are suspended and all other high-criticality tasks are assumed to exhibit high-criticality behaviors at the same time. In this paper, we propose a more realistic mixed-criticality model, called the flexible mixed-criticality (FMC) model, in which these two issues are addressed in a combined manner. In this new model, only the overrun task itself is assumed to exhibit high-criticality behavior, while other high-criticality tasks remain in the same mode as before. The guaranteed service levels of low-criticality tasks are gracefully degraded with the overruns of high-criticality tasks. We derive a utilization-based technique to analyze the schedulability of this new mixed-criticality model under EDF-VD scheduling. During run time, the proposed test condition serves an important criterion for dynamic service level tuning, by means of which the maximum available execution budget for low-criticality tasks can be directly determined with minimal overhead while guaranteeing mixed-criticality schedulability. Experiments demonstrate the effectiveness of the FMC scheme compared with state-of-the-art techniques.
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