Search

Gasoline compression ignition combustion is a new combustion mode with great development potential and is highly influenced by fuel reactivity and injection strategy. This paper coordinates the fuel octane number and single-injection timing to operate gasoline compression ignition combustion with high efficiency in a wide load range, with the speed fixed at 1500 r/min. The primary reference fuels with octane numbers 60, 70, 80, and 90 were used, labeled as PRF60, PRF70, PRF80, and PRF90, respectively. The results proved that under steady-state conditions where the speed and load changed slightly, taking the fuel economy and combustion and emission performance into account, PRF60 and PRF70 should be applied at a load lower than 2 bar and 2–8 bar, respectively, and the start of injection timing should be set at 13 °CA before top dead center. When the load is higher than 8 bar, PRF90 should be applied at the start of injection timing of 11 °CA before top dead center. It is noteworthy that PRF70 under medium-load conditions could achieve the indicated thermal efficiency of up to 47%. The injection timing of PRF90 was limited to 9–1711 °CA before top dead center due to the limit of the peak value of pressure rise rate, whereas PRF60 had a wider injection timing boundary than PRF90.

Gasoline compression ignition (GCI) is a highly feasible way to obtain high efficiency and low emissions simultaneously without many modifications of standard diesel engines. Exhaust gas recirculation (EGR) is an indispensable technology to achieve high efficiency and low emissions. A series of experimental studies were carried out to investigate the co-effect of EGR and fuel octane number on GCI combustion and emissions under all loads. Four primary reference fuels (PRF) with the research octane number of 90, 80, 70 and 60 were applied in this paper, which were denoted as PRF90, PRF80, PRF70 and PRF60. The results showed that high efficiency and low NOx emissions could be obtained under all loads by adjusting fuel octane number and EGR rate. PRF70 obtained the indicated thermal efficiency of above 47% by using the EGR rate of 30% and 40% under 6 bar and 8 bar, respectively. The increase in the EGR rate could decrease the oxygen content, thus reducing the NOx emissions. The EGR rate of 30% under 4–6 bar and the EGR rate of 40% under 8–12 bar could reduce the NOx emissions to below 300 ppm and 500 ppm, respectively. The effect of EGR on particle emissions was different under different loads. The increasing EGR rate reduced the particle emissions under low and medium loads, but increased the particle emissions under high loads due to the low volumetric efficiency. In addition, PRF90 with lower reactivity produced more methane, isopentane and aldehyde emissions than other fuels.

Gasoline compression ignition (GCI) is a promising advanced combustion mode to improve the fuel economy and reduce emissions. The intake conditions have significant effects on GCI combustion. To explore the proper intake conditions and fuels to achieve high efficiency under all loads, several experimental tests were carried out to investigate the effects of intake pressure and intake temperature on GCI combustion and emissions in this paper. Four primary reference fuels (PRF) with the research octane number (RON) of 90, 80, 70 and 60 were applied in this paper, which are recorded as PRF90, PRF80, PRF70 and PRF60. The results show that high efficiency under all loads could be achieved indeed by choosing proper intake pressure, intake temperature and fuels. The increase in intake pressure could significantly improve the fuel economy and decrease the CO, THC and NOx emissions. The increase in intake temperature increased the thermal efficiency under low loads and decreased the CO and THC emissions, but increased the NOx emissions simultaneously. However, with the increase in loads, the increased intake temperature reduced the volumetric efficiency, thus worsening the fuel economy. In addition, the influence of intake temperature on GCI combustion decreased with the decrease in RON. In general, high efficiency could be achieved by applying PRF70 and intake heating under low loads, as well as PRF70 under medium loads and PRF90 under high loads without intake heating, combined with supercharge under all loads. The highest indicated thermal efficiency (ITE) could reach 47% with PRF70 under medium loads.

Background This study aimed to classify relapsed retroperitoneal liposarcoma (RLS) as new primary (NP) or true recurrence (TR) and to assess the implications for therapeutic management of these classifications. Methods Patients with recurrent RLS were classified as NP if the relapse was different from the former tumor’s pathology subtype and anatomical location. Kaplan-Meier curves were adapted to estimate relapse-free survival (RFS), and logistic regression analysis was used to explore the factors related to NP.Results Total 177 patients with relapsed RLS were included in this study. The median tumor sizes were 16 cm (IQR, 13-22 cm, NP) and 18 cm (IQR, 12-25 cm, TR) (P=0.003). Multifocal tumors (89.2% vs 73.8%, P=0.011) and multiple pathology subtypes (52.7% vs 31.1%, P=0.004) were more common in the NP group and tended to invade wider anatomical areas (85.1% vs 71.8%, P=0.037). The median RFS was 17 months (IQR, 7-35 months) in the NP group and 12 months (IQR, 5-23 months) in the TR group, and NP patients showed a longer RFS than TR patients (P=0.004). When the log-rank test was conducted, low-grade pathology, tumor growth rate ≤ 1.25 cm/month and tumor size ≤ 16.5 cm had a significant influence on the NP phenomenon (P=0.015, 0.019, and 0.028, respectively). Logistic regression analysis illustrated that current surgeries, pathology subtype varieties and pathology grade were independent risk factors for NP (P=0.017, 0.019, and 0.025, respectively).Conclusion NP patients have longer RFS than TR patients, and their tumors tend to have multiple pathology subtypes and tumors and are more likely to invade wider anatomical areas. This classification contributes to a better understanding of RLS and provides new evidence for different therapeutic management of relapsed tumors.

In recent years, electric vehicle ownership keeps rising. Meanwhile, the attention on post-collision safety of electric vehicles is becoming higher and higher. This paper proposes the necessity for adding rear collision requirements for electric vehicles, analyzes improvement schemes for four anti-HV electric shock protection measures and puts forward the idea of equivalent test on the basis of analysis of post-collision electrical safety of electric vehicles at home and abroad, which can provide reference for guiding product design of electric vehicles and perfecting applicable standards and regulations. In the meantime, the study achievements will be applied to revision of national standard GB/T 31498-2015 in China.

Rice-fish system is the first globally important agricultural heritage system (GIAHS) and could be a potential option to improve modern rice production. This paper investigates energy flows and eco...

Diesel fuel mainly contains n-alkanes, iso-alkanes, cycloalkanes and aromatics, and varies with the source of crude oil and refining process. Although satisfying the same emission regulation, the particulate matter (PM) emissions and unregulated gaseous emissions of diesel fuel maybe vary a lot due to different fuel components. A series of experiments was conducted on a single-cylinder diesel engine fueled with diesel respectively blending with 10% and 20% fuel components to study the aldehyde, olefins, methane emissions and particulate matter (PM) emissions under engine loads from indicated mean effective pressure (IMEP) 1 bar to 8 bar. In this study, n-dodecane, iso-dodecane, tetralin and decalin were chosen to represent n-alkanes, iso-alkanes, aromatics and cycloalkanes, respectively. The results show that when IMEP less than 4 bar, the aldehydes emissions are relatively high even above 100 ppm. Blending fuel components in diesel causes the aldehydes emissions increasing except for n-alkanes. At low load from IMEP 1 to 3 bar, as blending ratio increase, aromatics and iso-alkanes noticeably worsen the hydrocarbon emissions especially. The hydrocarbon emissions of diesel/20% iso-dodecane and diesel/20% tetralin are respectively more than twice over those of diesel/10% iso-dodecane and diesel/10% tetralin. Aromatics and cycloalkanes have relatively high-level particle numbers which mainly distribute in nucleation mode with diameter ranging from 10 nm to 50 nm at IMEP 1 bar and 2 bar because of their lower H/C ratio leading to a tendency for precursor formation. At heavy load, the particle number presents a regular pattern that n-alkanes > cycloalkanes > iso-alkanes > aromatics and the peak value of particle size distribution moving towards to the right side due to prolonged combustion duration resulting in more time to polymerize.

In this paper, effects of different components in gasoline fuel on GDI engine emission characteristics were investigated. To simplify this investigation, model fuel CDTRF (composed of n-heptane, iso-pentane, diisobutylene, cyclohexane and toluene) instead of real gasoline fuel were used. To see how components of gasoline fuel affect engine performances, iso-pentane, diisobutylene, cyclohexane or toluene in CDTRF was substituted by other iso-alkanes, olefins, naphthenes and aromatics for comparative researches. N-heptane fraction is varied to balance fuel octane number. It is found that variation of fuel components obviously affect engine regulated and unregulated emissions. While, such effects vary when engine operation condition varies and are more distinct under lower engine speed or load conditions. Fuel components affect engine emission not just simply via chemical manner, but also through accompanying thermal-power process (cylinder pressure and temperature history). Thus variation of fuel components remarkably affects engine NOx emission. Alkanes, olefins and alkynes, aromatics contribute most to VOC emission followed by aldehydes. While, proportion of alcohols in VOC is negligible. However, variation of fuel components does not remarkably affect the proportion of alkanes, olefins and alkynes, aromatics as well as aldehydes in VOC although it affects total VOC emission obviously. Olefins and alkynes contribute most to OFP followed by aromatics and aldehydes. The contribution of alkanes is relatively low although it takes significant proportion in VOC. While, variation of fuel components remarkably affects total OFP of VOC though it does not obviously affect OFP composition. According to the results, it is hinted that more short chain i-paraffins and less branch chained cyclohexane in gasoline fuel would potentially help to reduce OFP of VOC.

In this paper, a simple, environmentally friendly, fluorine-free, economical and effective hydrophobic modification method for melamine sponge (MS) with cobalt oxyhydroxide (CoOOH) and stearic acid (STA) was developed. The 3D pine needle-like hierarchical micro-nanostructure CoOOH coated onto the framework of MS as superhydrophobic materials were successfully constructed and synthesized by low temperature hydrothermal method. By combining the high porosity, superior elasticity, and mechanical stability of the MS with the nanometer scale roughness of CoOOH and low surface energy of STA, the modified CoOOH@STA@MS not only has superhydrophobic surface with the water contact angle of 155°, but also shows outstanding adsorption performance towards the various organic solvents/oils (absorption weight ranging from 20 to 50 times of its own) and excellent recyclability. Additionally, the modified MS can be used as an efficient oil pollutant removal equipment for continuous oil-water separation with the help of peristaltic pump. Furthermore, the CoOOH@STA@MS could be able to separate immiscible oil-water mixture as well as surfactant-stabilized water-in-oil emulsions. All the advantages indicate that the superhydrophobic sponge is the ideal material for oil spills treatment and environmental control.

Aromatics are parts of the main components in gasoline which play important roles in affecting engine performances. Short carbon chain aromatics (C8/C8-) takes more part of aromatics in gasoline. In this paper, the effects of toluene, ortho-xylene and ethylbenzene on engine combustion, emission and thermal efficiency are experimentally investigated. Gasoline and three quinary gasoline model fuels containing each of these three aromatics, with diisobutylene, cyclohexane, isooctane, n-heptane being the other four components, are used to support this research. Results show that all the aromatics favor engine combustion and particulate emission while aggravate THC and CO emissions. Toluene, ethylbenzene and ortho-xylene do not obviously affect NOx emission under lower engine speed. However, ethylbenzene and ortho-xylene elevate engine NOx emission much more than toluene does under higher engine speed conditions. Alkenes and alkanes take the vast majority of VOC emission, followed by aromatics and aldehydes. Yet, alkenes take the most responsibility on OFP followed by aldehyde, and then aromatics, alkanes. Ethylene is the major composition of alkenes while formaldehyde contributes the most to aldehydes emission. In compare, toluene would propel alkenes and aldehydes in VOC emissions more than ethylbenzene and ortho-xylene do, however, it greatly alleviates particulate emission. Toluene tends to improve thermal efficiency under low engine speed conditions while ortho-xylene and ethylbenzene improve it under higher engine speed conditions. Results from this paper indicates that short chain aromatics affect engine combustion and emission a lot. So, varying short chain aromatics in gasoline fuel is of great importance in adjusting fuel properties.

Olefins are part of the most important components in gasoline fuel. In this paper, olefin component diisobutylene (DIB), 1-pentene and 1-hexene are involved into research. Three quinary gasoline model fuels containing each of these three olefins are used to support this research. Results prove these three olefins exhibit comparable effects on engine combustion and regulated emissions. However, their differences in affecting VOC and particulate matter emissions are of great significance. DIB leads to higher ethane emission while 1-hexene results in remarkably lower acetylene emission. 1-pentene generally leads to lower formaldehyde and acetaldehyde emissions. Nevertheless, these three olefins lead to comparable total VOC emissions. Further analyses show that alkane, olefin and aromatics take the most part of VOCs while olefin in emission take the most responsibility of ozone formation potential. Although 1-pentene in gasoline does not lead to the lowest VOC emissions, it results in the lowest OFP value when compared with DIB and 1-hexene. Such a finding signifies that gasoline with more 1-pentene content help to alleviate emission photochemical effect when compared with olefin content DIB or 1-hexene, which hints that gasoline with C5 olefin might be favorable than C6 olefin content when OFP of engine VOC emission is considered.

In this study, a kind of alkaline electrolyzed waters with the pH of 10.5 was used to enhance the sulfate resistance properties of concrete with mineral admixture at different proportioning. The results showed that Alkaline electrolyzed water in concrete can activate the pozzolanic effect of mineral admixtures, leading to an increase of compressive strength. The compressive strengths of electrolyzed water concrete (DJ) were all high than those of natural tap water concrete (TW) at same mineral admixture proportion. Through 120 times of sulfate attack cycles, the sulfate resistance coefficients of TW concrete with different proportions were 90.4~93.7%, and those of DJ concrete is 94.7~96.8%. The sulfate corrosion resistance property of DJ concrete was improved. The corrosion products AFt and gypsum on the surface of concrete were formed by the reaction of Ca2+ in cement paste and free SO4 2- infiltrated into the solution, which would further deepen the internal Ca2+ migration. In order to maintain the overall charge balance, K+ ions in alkaline electrolyzed water moved in, so as to slow down the corrosion of concrete. The SEM micromorphology showed that the internal structure of alkaline electrolyzed water concrete was more dense and compact, the porosity is relatively lower, which was less affected by sulfate corrosion. The microstructure of DJ concrete with mineral admixtures was more developed and denser than TW concrete.

Spark-ignition (SI) aviation piston engines are widely used on light helicopters and unmanned aerial vehicles (UAVs) because of the high-power density and ultra-high cost performance. Kerosene with high flash point is expected to improve safety of aforementioned aircrafts by replacing gasoline. However, in spark-ignition mode, kerosene is difficult to mix and is easy to knock. Short-chain alcohols have high volatility and octane number which can just make up for some defects of kerosene. In this paper, three kinds of alcohols including ethanol, n-propanol and n-butanol were blended with aviation kerosene (RP-3) by volume fraction of 30%, 50%, 70%, respectively. The combustion and emission characteristics of the blended fuels were deeply studied on a typical spark-ignition aviation piston engine. Meanwhile, engine performance fueled with commercial gasoline was also tested for comparison. Results indicated that alcohol/kerosene blends could reach higher brake thermal efficiency (BTE) (alcohol ratio ≥50%) compared to gasoline. Carbon monoxide (CO) and nitrogen oxides (NOx) emissions of blended fuels expressed dramatically descending. With the increase in alcohol ratio, the CO, hydrocarbons (HC) and soot emissions gradually decreased. The brake thermal efficiency showed an upward trend with the increase of alcohol ratios. The brake thermal efficiency of E70, P70 and B70 were increased by 2.15%, 3.52% and 6.51%, and the CO emissions of E70, P70 and B70 were reduced by 39.8%, 38.5% and 49.0%, respectively, compared to those of gasoline. Notably, n-butanol/kerosene blends exhibited the better combustion and emission characteristics, which had the higher efficiency and lower CO, HC and soot emissions.

The effective mineral admixture in mortar can consume the calcium hydroxide produced by hydration reaction because of pozzolanic effect. For high volume mineral admixture mortar, when the replacement ratio exceeds a certain ‘threshold’ value, the supply of Ca(OH)2 amount is insufficient, the superfluous and ineffective mineral admixture will no longer react in mortar but as fine aggregate. This study presents an experiment study on the threshold value of effective replacement ratio of fly ash mortar by the comprehensive analysis of Ca(OH)2 amount and consumption curves. Under the conditions of different curing temperature, the effective replacement ratios of fly ash mortar have been determined ultimately. The results showed that Ca(OH)2 amount and consumption in mortar both decreased with replacement ratio. For fly ash mortar, at 20°C curing temperature, when the replacement ratio was less than 40%, the Ca(OH)2 amount decreased obviously with replacement ratio. However, when replacement ratio was more than 40%, Ca(OH)2 amount at 91d changed slightly with replacement ratio, the Ca(OH)2 amount was consumed to a limit value at this time. Under the condition of 30°C curing temperature, when the replacement ratio exceeded 30%, the change of Ca(OH)2 amount with replacement ratio was close to a straight line, the superfluous fly ash no longer consumed Ca(OH)2 basically. Moreover, the consumption of Ca(OH)2 was not much difference to the Ca(OH)2 amount at the same replacement ratio under the condition of 20°C curing temperature. This result has a great significance on effective utilization of mineral admixtures in engineering application.

As a renewable fuel, butanol has a higher energy density than short-chain alcohols, and can be mixed with diesel in any proportion. To analyze the particulate matter emissions of butanol isomer in compression ignition engines, in this paper, the four butanol isomers were blended with diesel (25 vol%) named as n-butanol/diesel, s-butanol/diesel, i-butanol/diesel and t-butanol/diesel. The characteristics of particulate matter emissions were studied under a wide range of engine loads (3bar–9bar) and exhaust gas recirculation (EGR) rates (0%–60%). The results revealed that for all tested fuels as indicated mean effective pressure (IMEP) increased, particulate matter emissions first decreased and then increased. Compared to diesel under low load condition (IMEP = 3bar), the blending of butanol isomers had limited effect on particulate matter emissions. Among them, t-butanol increased the peak of particulate size distribution. When the engine load is higher than IMEP of 6 bar, the blending of butanol isomer significantly improved the particulate matter emissions. For IMEP fixed at 8bar, increasing the EGR rate made the particulate matter increase, especially for direct injection diesel. Butanol isomer/diesel blends can achieve low NOx and significantly improves particulate matter emissions in low temperature combustion mode (EGR = 60%). When EGR rates higher than 30%, the butanol isomer/diesel blends had a much smaller GMD than neat diesel. A comprehensive investigation of the four butanol isomer/diesel blends showed that t-butanol always had the highest particles than other butanol isomers under different EGR rates.

Three kinds differently structural 3D woven fabrics with the basalt fiber filaments tows as warp and weft yarn were fabricated on common loom by reasonable design. And, three kinds differently structural 3D woven basalt fiber composite materials were obtained with vinyl ester resin as matrix materials and 3D woven fabrics as reinforced materials, by VARTM molding process (vacuum assisted resin transfer molding process). Then, the tensile and bending properties of three kinds differently structural 3D woven basalt fiber composite materials were tested through the universal testing machine. Results were shown that the 3D woven basalt fiber composite materials had excellent mechanical properties, but the different structures of 3D woven fabrics as reinforced materials shown a big difference on mechanical properties. As follows, the modulus of elasticity for tensile and modulus of elasticity for bending of the 3D orthogonal structure basalt fiber composite materials were the greatest, and that of the 3D throughout angle interlocking structure basalt fiber composite materials was the smallest. Meanwhile, the tensile elongation at break of the 3D throughout angle interlocking structure basalt fiber composite materials were the largest and that of the 3D layered angle interlocking structure basalt fiber composite materials was the smallest.

Electric vehicles have the feature of being quiet when running, thus may led to high potential risk of traffic accident between cars and pedestrians. To avoid pedestrian injuries, many country tends to force auto manufacturers to equip their cars an acoustic vehicle alerting system for indication purpose. This paper intend to give a brief introduction of related standards and regulations developed or underway, deliver comprehensive comparison in technical aspects, and finally offers a broad view of the state of art of this realm.

The aim of this study was to analyze the relationship between oolong tea drinking and bone mineral density in postmenopausal Han Chinese women, while living and diet habits, fertility, disease elements and other baseline conditions were controlled. One group included 124 cases who routinely drank oolong tea, and the other included 556 who did not drink tea. Data were collected on participant age, lifestyle habits, fertility condition, disease elements, and lumbar, and hip bone densities. It was found that the bone densities of the greater trochanteric bone in tea drinkers were higher (0.793 ± 0.119 kg/cm(2)) than that in non-tea drinkers (0.759 ± 0.116 kg/cm(2), F = 6.248, p = 0.013). Similarly, the bone density of Ward's triangular bone in tea drinkers was higher (0.668 ± 0.133 kg/cm(2)) than that in non-tea drinkers (0.637 ± 0.135 kg/cm(2), F = 6.152, p = 0.013). Oolong tea drinking could help prevent bone loss in postmenopausal Chinese women.