A general approach to the real-time estimation of the complete traffic state in freeway stretches is developed based on the extended Kalman filter. First, a general stochastic macroscopic traffic ...flow model of freeway stretches is presented, while some simple formulae are proposed to model real-time traffic measurements. Second, the macroscopic traffic flow model along with the measurement model is organized in a compact state-space form, based on which a traffic state estimator is designed by use of the extended-Kalman-filtering method. While constructing the traffic state estimator, special attention is paid to the handling of the boundary conditions and unknown parameters of the macroscopic traffic flow model. A number of simulations are conducted to test the designed traffic state estimator under various traffic situations in a freeway stretch with on/off-ramps and a long inter-detector distance. Some key issues are carefully investigated, including tracking capability of the traffic state estimator, comparison of various estimation schemes, evaluation of different detector configurations, significance of the on-line model parameter estimation, sensitivity of the traffic state estimator to the initial values of the estimated model parameters and to the related standard deviation values, and dynamic tracking of time-varying model parameters. The achieved simulation results are very promising for the subsequent development and testing work that is briefly outlined.
Microwave-assisted functionalization of single-wall carbon nanotubes (SWNTs) in a mixture of nitric and sulfuric acids was carried out to synthesize highly water-dispersible nanotubes. Stable ...concentrations as high as 10 mg/mL were obtained in deionized water that are nearly 2 orders of magnitude higher than those previously reported. This was after only 3 min of functionalization reaction. Fourier transform infrared spectra showed the presence of carboxylated (-COOH) and acid sulfonated (-SO2·OH or -SO3 - H+) groups on the SWNTs. On the basis of elemental analysis, it was estimated that one out of three carbon atoms was carboxylated, while one out of 10 carbon atoms was sulfonated. The Raman spectra taken both in aqueous dispersion and in the solid phase indicated charge transfer from the SWNT backbone to the functional groups. Scanning electron microscope images of thin films deposited from an aqueous suspension showed that the SWNTs were aligned parallel to one another on the substrate. The images also indicated some reduction in average length of the nanotubes. Transmission electron microscope images of thin films from a dilute methanol dispersion showed that the SWNTs were extensively debundled. Laser light scattering particle size measurements did not show evidence for the existence of particles in the 3−800 nm size range, indicating that the functionalized SWNTs might have dispersed to have formed a true solution. Moreover, the microwave-processed SWNTs were found to contain significantly smaller amounts of the original iron catalyst relative to that present in the starting nanotubes. The electrical conductivity of a thermally annealed thin membrane obtained from the microwave-functionalized SWNTs was found to be the same as that of a similar membrane obtained from a suspension of the starting nanotubes.
Effect of probiotics for common carp (
Cyprinus carpio) based on growth performance, feed utilization (feed conversion ratio, FCR) and digestive enzyme (protease, amylase and lipase) activities was ...investigated. The photosynthetic bacteria and
Bacillus sp. isolated from common carp ponds were added to carp basal diets as the probiotics in three forms: 1
g
kg
−1 lyophilized photosynthetic bacteria cells (PSB), 1
g
kg
−1 lyophilized
Bacillus sp. (B) and their mix. Twelve aquaria with replicates for treatment and control were used. After a 60-day feeding experiment with probiotics supplemented and non-supplemented control diets, the diets supplemented with probiotics showed significantly better results of growth performance and FCR than those with the basal diet (control). Mean digestive enzyme activities of all probiotics treatment groups were significantly different (P<0.05) with that of the control. The protease activity was remarkably higher in the mix and
Bacillus sp. compared with PSB and control. However, there was no difference between the mix and
Bacillus sp. As for amylase and lipase, assays showed higher activity in the mix as compared to the rest. In conclusion, it showed that probiotics highly increased the growth performances and digestive enzyme activities, and decreased FCR. Furthermore, different probiotics forms indicated different performances and the mix produced the best results.
The effect of probiotic,
B. coagulans SC8168, as water additive on larvae shrimp (
Penaeus vannamei) based on water quality, survival rate and digestive enzyme activities was investigated at ...ontogenetic stages (Z
3, M
3, PL
1–2 and PL
7–8). Twelve tanks with three replicates for each treatment group and control group were used. The treatments consisted of three SC8168 levels at an initial concentration of 1.0
×
10
5 cfu ml
−
1
(T-1), 5.0
×
10
5 cfu ml
−
1
(T-2) and 1.0
×
10
6 cfu ml
−
1
(T-3) and one control (without any probiotic), and were conducted every day. Addition of the probiotic significantly increased survival rate (
P
<
0.05) for all treatments over controls. However, no significant difference was found between T-2 and T-3. At early larval stages (Z
3 and M
3), protease activity in shrimp was not significantly different among probiotic treatments and control. At the subsequent ontogenetic stages (PL
1–2 and PL
7–8), the highest protease activity was observed in T-2 and there was a significant difference (
P
<
0.05) between the treatment and the control. Similar results were observed in T-3 at PL
7–8 stage (
P
<
0.05). Amylase activity in T-2 at Z
3, M
3, PL
1–2 and PL
7–8 stages was significantly higher (
P
<
0.05) than that in the control. The amylase activity was also increased significantly (
P
<
0.05) in T-3 than the control except the M
3 stage. As for the lipase activity, assays showed a significant difference (
P
<
0.05) in groups treated with SC8168 as compared with the control except the initial stage (Z
3). However, a concentration response of probiotic strains in T-1, T-2 and T-3 was not observed in the present research. The results from this study suggest that
B. coagulans SC8168 supplemented at a certain concentration could significantly increase survival rate and some digestive enzyme activities of
P. vannamei larvae.
Agriculture is very sensitive to climate change, and correct forecasting of climate change is a great help to accurate allocation of irrigation water. The use of irrigation water is influenced by ...crop water demand and precipitation. Potential evapotranspiration (ET0) is a measure of the ability of the atmosphere to remove water from the surface through the processes of evaporation and transpiration, assuming no control on water supply. It plays an important role in assessing crop water requirements, regional dry–wet conditions, and other factors of water resource management. This study analyzed the spatial and temporal evolution processes and characteristics of major meteorological parameters at 10 stations in the Loess Plateau of northern Shaanxi (LPNS). By using the Mann–Kendall trend test with trend–free pre–whitening and the ArcGIS platform, the potential evapotranspiration of each station was quantified by using the Penman–Monteith equation, and the effects of climatic factors on potential evapotranspiration were assessed by analyzing the contribution rate and sensitivity of the climatic factors. The results showed that the climate in LPNS has become warmer and drier. In terms of the sensitivity of ET0 to the variation of each climatic factor in LPNS, relative humidity (0.65) had the highest sensitivity, followed by daily maximum temperature, wind speed, sunshine hours, and daily minimum temperature (−0.05). In terms of the contribution rate of each factor to ET0, daily maximum temperature (5.16%) had the highest value, followed by daily minimum temperature, sunshine hours, relative humidity, and wind speed (1.14%). This study provides a reference for the management of agricultural water resources and for countermeasures to climate change. According to the climate change and the characteristics of the study area, farmers in the region should increase irrigation to guarantee crop water demand.
Display omitted
•The Loess Plateau of northern Shaanxi (LPNS) experienced a warmer and drier period.•Sensitivity and contribution rate analysis were used to explore the driving factor of ET0.•ET0 showed a significant upward trend in the northern part of LPNS.•ET0 was most sensitive to the variation of relative humidity in LPNS。•Maximum temperature had a higher contribution rate to the variation of ET0 in LPNS
Antenatal corticosteroid therapy (ACT) is used clinically to prepare the fetal lung for impending preterm birth, but animal and human studies link corticosteroids to smaller birth size. Whether ACT ...is associated with birth size is debated; therefore, we assessed differences in birth size in treated versus untreated pregnancies.
This observational register-based study used data from the Finnish Medical Birth Register (FMBR) covering all births in Finland (January 1, 2006-December 31, 2010). We used unadjusted and adjusted regression analyses as well as propensity score matching (PSM) to analyze whether birth size differed by ACT exposure. PSM provides a stringent comparison, as subsamples were created matched on baseline and medical characteristics between treated and untreated women. All analyses were stratified by timing of birth. The primary study outcome was birth size: birth weight (BWT), birth length (BL), ponderal index (PI), and head circumference (HC) measured immediately after birth and recorded in the FMBR. Additional analyses explored indicators of neonatal health in relation to ACT exposure and birth size. A total of 278,508 live-born singleton births with ≥24 gestational completed weeks were registered in the FMBR during the 5-year study period. Over 4% of infants were born preterm, and 4,887 women were treated with ACT (1.75%). More than 44% of the exposed infants (n = 2,173) were born at term. First, results of unadjusted regression analyses using the entire sample showed the greatest reductions in BWT as compared to the other analytic methods: very preterm -61.26 g (±SE 24.12, P < 0.01), preterm -232.90 g (±SE 17.24, P < .001), near term -171.50 g (±SE 17.52, P < .001), and at term -101.95 g (±SE 10.89, P < .001). Second, using the entire sample, regression analyses adjusted for baseline and medical conditions showed significant differences in BWT between exposed and unexposed infants: very preterm -61.54 g (±SE 28.62, P < .03), preterm -222.78 g (±SE 19.64, P < .001), near term -159.25 g (±SE 19.14, P < .001), and at term -91.62 g (±SE 11.86, P < .03). Third, using the stringent PSM analyses based on matched subsamples, infants exposed to ACT weighed less at birth: -220.18 g (±SE 21.43, P < .001), -140.68 g (±SE 23.09, P < .001), and -89.38 g (±SE 14.16, P < .001), born preterm, near term, and at term, respectively. Similarly, significant reductions in BL and HC were also observed using the three analytic methods. There were no differences among postterm infants regardless of analytic method. Likewise, we observed no differences with respect to PI. Additional analyses showed that exposed and unexposed infants had generally similar Apgar scores at birth, yet the ACT-treated infants received greater medical care during the first 7 days of life and beyond. Our study is mainly limited by lack of data in FMBR specifying the interval between treatment and birth as well as other potential confounders that could not be tested.
In this study, ACT was consistently associated with reduction in birth size for infants born preterm, near term, or at term. Further investigation is warranted alongside reevaluation of guidelines. Efforts need to be made to correctly identify and target patients who will deliver preterm. Reduced growth should be considered when deliberating early care decisions.
•GHG emissions and crop water demand under various scenarios were evaluated.•Changes in planting structure in the study area increased water demand and GHG emissions.•The expansion of the planting ...area is the main reason for increasing water demand and GHG emissions.•Rice has the greatest impact on GWP during the study period in Heilongjiang.
The agriculture sector is one of the largest users of water and a significant source of greenhouse gas (GHG) emissions. The development of low-GHG-emission and water-conserving agriculture will inevitably be the trend in the future. Because of the physiological differences among crops and their response efficiency to external changes, changes in planting structure, climate and input of production factors will have an impact on regional agricultural water use and GHG emissions. This paper systematically analyzed the spatial-temporal evolution characteristics of crop planting structure, climate, and production factor inputs in Heilongjiang Province, the main grain-producing region of China, from 2000 to 2015, and quantified the regional agricultural water use and GHG emissions characteristics under different scenarios by using the Penman-Monteith formula and the Denitrification-Decomposition (DNDC) model. The results showed that the global warming potential (GWP) increased by 15% due to the change in planting structure. A large increase in the proportion of rice and corn sown was the main reason. During the study period, regional climate change had a positive impact on the water-saving and emission reduction of the agricultural industry. The annual water demand per unit area decreased by 19%, and the GWP decreased by 12% compared with that in 2000. The input of fertilizer and other means of production will have a significant impact on GHG emissions from farmlands. The increase in N fertilizer input significantly increased N2O emissions, with a 5% increase in GWP. Agricultural water consumption and carbon emissions are affected by changes in climate, input of means of production, and planting structure. Therefore, multiple regulatory measures should be taken in combination with regional characteristics to realize a new layout of planting structure with low emissions, water conservation, and sustainability.
•A series of parametric study was carried out to investigate effect of geometry and imperfections on column strength.•α and χ are positively correlated: χ increases at different rates as α ...increases.•χ decreases with the increase of β at very low rate and the effect of β on χ is not very obvious.•Residual stress does not always have negative effect on χ.
The paper describes a numerical study on columns fabricated from high strength steel (HSS) plates with nominal yield stress of 690 MPa. The study comprised 4 benchmark models validated by testing data and 144H-section parametric study models. The benchmark models were firstly created and validated against testing data for the accuracy. A full-scale parametric study was carried out to investigate effect of flange width/thickness ratio (α), web height/thickness ratio (β), geometrical imperfection (D) and residual stress (R) on overall buckling behaviour of the columns. The purpose of the study was to understand the relationship between section geometry, imperfections and column strength fabricated by welding from 690 MPa high strength steel plates. The H-section HSS columns were studied in this paper for the buckling behaviour along the minor axis in which direction those columns have smaller stiffnesses.
It is shown that all those factors can be classified into three groups according to their impact on column strength (expressed with strength reduction factor χ): favourable factor (α), adverse factor (β and D) and uncertain factor (R). α and χ are positively correlated: χ increases at different rates as α increases. It is an effective way to increase α to improve column strength when α is a small value. χ decreases with the increase of β at very low rate and the effect of β on χ is not very obvious. D could produce more pronounced deterioration effect on ultimate strength of columns with higher α. The effect of residual stress (R) on H-section column strength is related with α: for the columns with higher α value, higher residual stress could produce more serious strength reduction effect. Residual stress does not always have negative effect on χ. It could produce beneficial effect on the ultimate strength of high strength steel H-section columns as long as α is reasonably small.
The paper also shows a comparison of analysis results with existing standards including Eurocode 3 and GB50017-2017. For Eurocode 3, curve a0 can accurately predict χ with λ¯ when D = 0.03%. When D = 0.20%, curve b gives the best-fit prediction.
Nano-selenium (Se), with its high bioavailability and low toxicity, has attracted wide attention for its potential application in the prevention of oxidative damage in animal tissues. However, the ...effect of nano-Se of different sizes on the intestinal epithelial cells of the crucian carp (Carassius auratus gibelio) is poorly understood. Our study showed that different sizes and doses of nano-Se have varied effects on the cellular protein contents and the enzyme activities of secreted lactate dehydrogenase, intracellular sodium potassium adenosine triphosphatase, glutathione peroxidase, and superoxide dismutase. It was also indicated that nano-Se had a size-dependent effect on the primary intestinal epithelial cells of the crucian carp. Thus, these findings may bring us a step closer to understanding the size effect and the bioavailability of nano-Se on the intestinal tract of the crucian carp.
Traffic congestion in urban road and freeway networks leads to a strong degradation of the network infrastructure and accordingly reduced throughput, which can be countered via suitable control ...measures and strategies. After illustrating the main reasons for infrastructure deterioration due to traffic congestion, a comprehensive overview of proposed and implemented control strategies is provided for three areas: urban road networks, freeway networks, and route guidance. Selected application results, obtained from either simulation studies or field implementations, are briefly outlined to illustrate the impact of various control actions and strategies. The paper concludes with a brief discussion of future needs in this important technical area.
PDF
