Particles larger than 10 nm from engine exhaust are gaining global concerns. In light of this, to investigate how EGR affects gasoline vehicle SPN10 (solid particles larger than 10 nm) emissions, ...seven gasoline vehicles (hybrid or conventional) were studied experimentally. The results revealed that EGR vehicles risk failing the current limit (6 * 1011 #/km) more than those without EGR if the cut-off size was tightened from 23 nm to 10 nm. More specifically, during the WLTC test, EGR increased the SPN10 emission factors by 2 ∼ 3 times depending on vehicle powertrains (conventional or hybrid). Notably, SPN10 emissions increased significantly when EGR was actively engaged but showed a decrease when the EGR rate remained constant. EGR and the enriched fuel-air mixture are the critical reasons for the increased SPN10.
An evaluation of the measurement uncertainty of on-road NOx emissions using portable emission measurement system (PEMS) based on real local testing data collected in China was carried out as per the ...type B method defined in the EN 17507 standard. The aim of this work was to quantify the “absolute” measurement uncertainty of PEMSs, which excluded “PEMS relative to laboratory constant volume sampler (CVS)” uncertainty from the calculation of on-road NOx measurement uncertainty using PEMSs. PEMS instruments from three mainstream manufacturers were employed. The zero drift of the NOx analyzers was evaluated periodically during the real driving emissions (RDE) test, and it was noticed that there was neither a linear nor step model of zero drift, with no correlation with the boundary conditions or measurement principle. Additionally, from the 256 valid RDE tests, the zero drift always ranged from 3.8 ppm to −3.8 ppm, and more than 95% of the span drifts were within a range of 1.5%. Based on the laboratory testing of ten vehicles using the worldwide harmonized light-duty vehicle test cycle (WLTC), the type B uncertainty of PEMS NOx measurements corresponding to China-6a and China-6b limits was assessed. An uncertainty of 26.5% for China-6a was found (NOx limit = 60 mg/km over the WLTC), which is very close to the 22.5% from the EU evaluation results (NOx limit = 80 mg/km over the WLTC); the uncertainty with respect to China-6b was found to be 42.8% because the type-I limit was tuned down to 35 mg/km. This result indicates that, with the ever-tightening regulatory limits of vehicle NOx emissions, big challenges will be posed in terms of the reliability of PEMS measurements, which requires PEMS manufacturers to improve the performance of the instruments and policymakers to refine the test procedures and/or result calculation method to minimize the impacts.
Most of the current, popular approaches to monitoring real driving NOx emissions are based on direct measurement. However, due to the uncertainty of sensor-based measurements, such methods cannot ...always be used to accurately screen out the malfunctions of an emission control system. In this paper, a random forest (RF) model which extracts information from on-board diagnostics (OBD) data streams transmitted by a remote emission management vehicle terminal (REMVT) is proposed to provide a specific emission method for the online screening of high NOx emissions. First, two particular forms of modeling, random forest and logistic regression (LR), are laid out as representatives of nonparametric models and specified linear models. These two models were trained, validated and compared using OBD data collected from three China-VI heavy-duty diesel vehicles (HDDVs). The results show that as a data-driven, highly adaptive and robust learning method, the RF model can more accurately identify an abnormal emission state. Finally, a further validation was conducted, in which another China-VI HDDV was tested in two typical states, including a fault state and a normal state. The results indicated that the RF model could clearly distinguish the out-of-control emission condition from the normal operation state. The outcome of this research verifies the feasibility of using a machine learning model to process remote OBD data on HD vehicles and to identify high emissions in the case of an in-use fleet. On this basis, more sophisticated combined models and multi-stage models could be developed.
The heavy-duty moving average window (MAW) method, used for heavy-duty diesel vehicle (HDDV) real driving emission certification, has been long criticized for its unreasonable results. To ...quantitively analyze the problem, causes, and impacts of the MAW method, five China VI HDDVs were tested under real driving conditions. The specific method and MAW method with different boundaries are applied for data analysis. The results illustrate that cold start occupied 40.82 ± 11.22% of the total NOx emission within 5.77 ± 1.21% of the duration. Compared to the specific method, the MAW result gap is observed varying from −16.92% to 100.24% and didn’t show any pattern. Three reasons could explain biased MAW results: the 20% power threshold excludes the cold data; the 90th accumulative percentile window brings large uncertainty to the result and leaves the highest 10% window without supervision; the initial data gets low utilization. The MAW method could lead to ineffective NOx supervision and exhaust cheating. The future emission limits and emission inventories based on these results are also less reasonable. The above-discussed three reasons and the cold start data exclusion should be considered together to consummate the MAW method. These results could be used for future emission legislation and NOx control optimization.
•China VI heavy-duty moving average window (MAW) method was evaluated quantitatively.•The cold-start occupied 40.82 ± 11.83% of the total NOx within 5.77 ± 1.34% of the duration.•The MAW method weakens the real driving tests due to its ineffective NOx supervision.•The power threshold and 90th percentile window bring large uncertainty to the result.•The MAW boundaries are closely coupled and they should be reconsidered together.
In this article, the impacts of varying CeO
2
contents and heat‐treatment procedures on the crystallization, microstructure, and dielectric characteristics of MgO–Al
2
O
3
–SiO
2
–TiO
2
–CeO
2
...(MASTC) materials are investigated. In this research, it is indicated that perrierite, rutile, and α‐cordierite are the major crystalline phases in the materials. An increased CeO
2
content promotes the formation of perrierite and inhibits the precipitation of α‐cordierite and rutile in the glass ceramics. An appropriate amount of CeO
2
content contributes to a dense microstructure and improves the dielectric characteristics of the samples. However, an excessive amount of CeO
2
deteriorates the densification and dielectric characteristics of the MASTC materials. Furthermore, heat‐treatment temperature and duration also have a significant impact on the crystallization, microstructure, and dielectric performance of the materials. The MASTC material with 20.2 wt% CeO
2
, heat‐treated at 1100 °C for a duration of 3 h, possesses superior characteristics with a density of 3.14 g cm
−3
, a permittivity of 11.1, and a
Q × f
factor of 17 357 (14 GHz).
In this article, the impacts of varying CeO2 contents and heat‐treatment procedures on the crystallization, microstructure, and dielectric characteristics of MgO–Al2O3–SiO2–TiO2–CeO2 (MASTC) ...materials are investigated. In this research, it is indicated that perrierite, rutile, and α‐cordierite are the major crystalline phases in the materials. An increased CeO2 content promotes the formation of perrierite and inhibits the precipitation of α‐cordierite and rutile in the glass ceramics. An appropriate amount of CeO2 content contributes to a dense microstructure and improves the dielectric characteristics of the samples. However, an excessive amount of CeO2 deteriorates the densification and dielectric characteristics of the MASTC materials. Furthermore, heat‐treatment temperature and duration also have a significant impact on the crystallization, microstructure, and dielectric performance of the materials. The MASTC material with 20.2 wt% CeO2, heat‐treated at 1100 °C for a duration of 3 h, possesses superior characteristics with a density of 3.14 g cm−3, a permittivity of 11.1, and a Q × f factor of 17 357 (14 GHz).
The MgO–Al2O3–SiO2‐based glass ceramics are exceptional dielectric materials. The dielectric characteristics of these glass ceramics are relevant to their crystalline phases. In this research, it is indicated that the crystalline phases in MgO–Al2O3–SiO2–TiO2–CeO2 glass ceramics are closely related to the heat‐treatment temperatures applied. As the temperature increases from 850 to 1200 °C, the perrierite, rutile, and α‐cordierite crystals successively precipitated in the glass ceramics.
The application of biochar is one of the promising management practices to alleviate soil acidification and improve soil fertility. However, it has been found to reduce the content of ammonium ...nitrogen (NH4+−N) in the soil, which is the most important form of nitrogen (N) for tea tree growth. To investigate the response of soil NH4+−N content to the combined application of biochar and pruned tea plant litter, a pot trial was performed with three treatments: control (CK); biochar (BC); biochar + tea plant litter (BC + L). Soil chemistry properties and ammonification rates were determined, and the microbial community composition was analyzed by high-throughput sequencing. The results showed that the NH4+−N content in BC + L treatment was 1.7–9.5 fold higher than CK and BC treatments after 15 days of application, with no difference in the proportion of ammonia oxidation phyla such as Nitrospirae. The proportion of soil fungus Ascomycota was strongly correlated with the content of soil available nitrogen (p = 0.032), and the relationship was well described by a linear equation (R2 = 0.876, p = 0.01). Further redundancy analysis revealed that soil pH, soil organic carbon (SOC), the ratio of SOC to total nitrogen and the ratio of SOC to alkaline hydrolyzable nitrogen appeared to be important factors influencing the separation of BC + L from CK and BC groups. In summary, the addition of biochar and pruned tea plant litter alters soil properties and may influence the composition of microorganisms with various trophic groups, thus affecting ecosystem function. Our results also highlight the importance of returning pruned materials with biochar application in tea plantation ecosystems.
To reduce the cost of oil exploitation, it is necessary to promote the development of cyclones for oil-water separation due to the increase of the water content in produced fluids. However, there are ...some limitations and disadvantages for the conventional separation device including bulky settling tanks and hydrocyclones. In this paper, a new axial inlet separator with two reverse flow outlets and a downstream flow outlet is introduced. In addition, an experimental system was designed and fabricated to investigate the effects of inlet flow rate, oil fraction, and a controlled split ratio on separation performance. The separator maintains high separation efficiency within the experimental range, namely water flow rate (4–7 m
3
/h), and oil fraction (1%–10%). Furthermore, the results show that a higher water flow rate and oil fraction will affect the separation efficiency. The change of a pressure drop in the separator was analyzed as well. Moreover, the controlled split ratio is a serious operating parameter, and a larger controlled split ratio is conducive to the separation performance.
Isolation and culture of spermatogonial stem cells (SSCs) are attractive for production of genetic modified offspring. In the present study, buffalo spermatogonial stem-like cells were isolated, ...cultured and expression pattern of different germ cell marker genes were determined. To recover spermatogonia, testes from age 3 to 7 months of buffalo were decapsulated, and seminiferous tubules were enzymatically dissociated. Two types of cells, immature sertoli cell and type A spermatogonia were observed in buffalo testes in this stage. Germ cell marker genes, OCT3/4 (Pou5f1), THY-1, c-kit, PGP9.5 (UCHL-1) and Dolichos biflorus agglutinin, were determined to be expressed both in mRNA and protein level by reverse transcription polymerase chain reaction and immunostaining in buffalo testes and buffalo spermatogonial stem-like cells, respectively. In the following, when the isolated buffalo buffalo spermatogonial stem-like cells were cultured in the medium supplemented 2.5% fetal bovine serum and 40 ng/mL glial cell-derived neurotrophic factor medium, SSCs proliferation efficiency and colony number were significantly improved than those of other groups (p<0.05). These findings may help in isolation and establishing long term in vitro culture system for buffalo spermatogonial stem-like cells, and accelerating the generation of genetic modified buffaloes.
To evaluate the efficacy of ultrasound guided quadratus lumborum block combined with non-steroidal anti-inflammatory drugs for postoperative analgesia in patients undergoing total hip arthroplasty.
...From January to June 2017, sixty American Society of Anesthesiologists (ASA) physical status Ⅰ to Ⅲ patients, aged 55-75 yr, scheduled for total hip arthroplasty, were randomly divided into control group(group N) and quadratus lumborum block (group R). Ultrasound guided quadratus lumborum block was implemented on the affected side at the end of operation.Then 30 ml 0.33% ropivacaine were administrated in group R, while the control group did not receive the same block. A sufentanil patient-controlled analgesia pump was connected to the patient. The rest visual analogue score (VAS) were recorded at 0 h(T(0)), 3 h(T(1)), 6 h (T(2)), 12 h(T(3)), 24 h (T(4)), 36 h (T(5)) and 48 h(T(6)) after sugery, the VAS scores on movement were evaluated at T(4), T(5) and T(6) time points.The consumption of sufentanil within each period time were recorded.The maximal flexion and abduction degrees of the hip joint were evaluated at 12, 24, 36 and 48 h after operation. The number of patients for rescue pain relief by intravenous analgesia pump during 24 h and 48 h after surgery were counted in both groups. The postoperative adverse effects and overall satisfaction in the two groups were recorded.
The VAS at rest in group R were 0.8±0.4, 1.0±0.3, 1.2±0.5, 2.0±0.5, 1.7±0.4 , 1.6±0.5 at T(1), T(2), T(3), T(4), T(5), T(6) respectively, and those in group N were 3.0±0.7, 3.5±0.9, 3.8±0.9, 3.3±1.1, 3.3±0.7, 3.0±0.7 at the same time points. The VAS at rest were lower in group R than those in control group at all time points (
=203.090, 216.354, 203.956, 35.548, 96.332, 80.577, all
<0.01). The VAS on movement in group R were 2.7±0.9, 2.9±0.7 , 2.0±0.6 at T(4), T(5), T(6) respectively , and those in group N were 6.0±1.5, 5.8±1.1, 4.5±1.0. The VAS on movement were also lower in group R than those in control group(
=154.561, 143.224, 141.479, all
<0.01). The maximum flexion degrees in group R were (61±12)degrees, (64±10)degrees, (69±15)degrees and(78±19)degrees at 12, 24, 36, 48 h after operation, and those were (45±11) degrees, (49±10)degrees, (52±12)degrees and(60±14)degrees at the same time points. The maximum flexion degrees in group R were increased more than control group at 12, 24, 36, 48 h after operation(
=34.981, 35.575, 52.106, 41.681, all
<0.01). The abduction degrees in group R were(22±6)degrees, (26±6)degrees, (27±8)degrees and(28±7)degrees at 12, 24, 36, 48 h after surgery, and those in group N were (14±5) degrees, (17±6)degrees, (20±6)degrees and(20±5)degrees. The abduction degrees in group R were increased more than those in group N(
=58.974, 33.402, 19.151, 20.575, all
<0.01). The rates of rescue analgesia for pain relief were 10% and 16.7% at 24 h and 48 h after operation respectively in group R, and those were 100% and 100% in group N. Compared to group N, the rates of rescue analgesia for pain relief in group R were significantly decreased (χ(2)=49.091, 42.857, all
<0.01). The incidences of postoperative nausea and vomiting, pruritus in group R were 3.3% and 3.3% respectively, and those in group N were 23.3% and 20.0%. The incidences of nausea and vomiting, pruritus in group R were lower than those in group N (χ(2)=5.192, 4.875, all
<0.01). The overall satisfaction scores in group R (3.7 ± 1.0 ) were higher than those (1.9±0.7) in the group N(
=7.841,
<0.01).
The quadratus lumborum block combined with parecoxib sodium for multimodal analgesia after total hip arthroplasty is effective and provides satisfactory analgesia.
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