67,362 research outputs found
Combustion characteristics of CAI combustion with alcohol fuels
No full textSAE paper 2010-01-0843: Copyright © 2010 SAE International. This paper is posted on this site with permission from SAE International, and is for viewing only. Further use and distribution of this paper is not permitted without permission from SAE.Due to its potential for simultaneous improvement in fuel consumption and exhaust emissions, controlled autoignition (CAI) combustion has been subject to continuous research in the last several years. At the same time, there has been a lot of interest in the use of alternative fuels in order to reduce reliance on conventional fossil fuels. Therefore, this experimental study has been carried out to investigate the effect of alcohol fuels on the CAI combustion process and on the resulting engine performance.
The experimental work was conducted on an optical single cylinder engine with an air-assisted injector. To achieve controlled autoignition, residual gas was trapped in the cylinder by using negative valve overlap and an intake air heater was used to ensure stable CAI combustion in the optical engine. Methanol, ethanol and blended fuels were tested and compared with the results of gasoline. The combustion processes were analysed through total chemiluminescence images captured with a high speed camera equipped with an intensifier. In addition, the effect of spark discharge was investigated.
The images show that CAI combustion of alcohol fuels was characterized with fast and early autoignition combustion compared with pure gasoline. Chemiluminescence of the gasoline fuel was most visible and it decreased with increasing percentage of oxygenated fuels. During the re-compression stroke, chemiluminescence images of the gasoline engine indicated the presence of oxidation reactions. In the presence of spark discharge, the location of charge ignition was dominated by spark discharge at the center of cylinder while simultaneous autoignition sites were found around the periphery of the combustion chamber for non-spark-assisted ignition
Hsiaotycoris Lu, Zhao & Cai
No full textHsiaotycoris Lü, Zhao & Cai, gen. nov. Type species. Hsiaotycoris tuberculatus Lü, Zhao & Cai, sp. n. Diagnosis. Medium sized. Head cylindrical with some tuberculate processes, subequal to or slightly longer than pronotum (Figs. 1, 5); first antennal segment with some distinct tuberculate processes (Figs. 2, 6), slightly longer than second segment, second segment subequal to third segment in length, fourth segment shortest; anterior portion of postclypeus prominently produced anteriorly, upper margin nearly straight (Figs. 12, 17); eyes of medium size, protruding laterally; ocelli small, widely separated; anteocular portion of head distinctly shorter than postocular, latter constricted behind eyes and subbasally; first rostral segment extending beyond anterior margin of eyes, second segment longest, longer than first and third segments combined, third segment shortest (Figs. 12, 17). Collar undeveloped; pronotum wider than long; transverse constriction situated behind middle in subapterous form (Figs. 1, 12) and before middle in macropterous form (Figs. 5, 17); anterior pronotal lobe scattered with some tubercles, lateral sides of low longitudinal median depression with symmetric smooth sculptures; lateral pronotal angles tuberculate, posterior margin nearly straight (Fig. 1, 5); scutellum unarmed; legs with some scattered tubercles and spines; fore leg moderately incrassate, with more tubercles and spines than mid and hind legs, inner surface of fore femur and fore tibia with two series of strong spines (Figs. 13, 19). Abdomen dilated laterally in subapterous form (Fig. 1) and nearly parallel laterally in macropterous form (Fig. 5). Distribution. China (Yunnan). Etymology. This genus is named in honor of the late Prof. T. Y. Hsiao for his great contribution to the study of Heteroptera. Masculine. Remarks. The general body plan of the female of the new genus is similar to that of Asiacoris Tomokuni & Cai, but the anterior portion of the postclypeus of the latter is distinctly bent upwards, and the ventral surfaces of the fore femur and fore tibia lack strong spines. The new genus is also allied to Tapirocoris Miller, Yangicoris Cai, Henricohahnia Breddin, Karenocoris Miller, and Malaiseana Miller. These genera can be distinguished with the following key.Published as part of Lü, Zhaozhi, Zhao, Ping & Cai, Wanzhi, 2006, Hsiaotycoris tuberculatus, a new genus and species of Harpactorinae (Heteroptera: Reduviidae) from China, pp. 33-41 in Zootaxa 1286 on page 34, DOI: 10.5281/zenodo.17350
Investigation of combustion and performance characteristics of CAI combustion engine with positive and negative valve overlap
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.In the first part of studies, Controlled Auto-Ignition (CAI) combustion was investigated in a Ricardo E6 single cylinder, four stroke gasoline engine. CAI combustion is achieved by employing positive valve overlap configuration in combination with various compression ratios and intake air temperature strategies. The CAI operational region is limited by engine load due to knock and partial burned boundaries. The combustion characteristics and emissions are studied in order to understand the major advantages and drawbacks of CAI combustion with positive valve overlap.
The enlargement of the CAI operational region is obtained by boosting intake air and external EGR. The lean-boosted operation elevators the range of CAI combustion to the higher load region, and the use of external EGR allows the engine to operation with CAI combustion in the mid range of region between boosted and N/A CAI operational range. The results are analyzed and combustion characteristics, performance and emissions are investigated.
A Ricardo Hydra single cylinder, four stroke optical gasoline engine with optical access is then experimented to investigate CAI combustion through negative valve overlap configuration and an intake heater. The effects of direct fuel injection timings spark timings and air/fuel ratio are studied by means of simultaneous incylinder heat release study and direct visualization, chemiluminescence techniques which uses full, OH radical and CHO species. Both heat release analysis and chemiluminescence results have identified the pressure of minor combustion during the NVO period. Both the charge cooling and local air/fuel ratio effects are also investigated by varying the quantity of direct air injection
Liangcoris Zhao, Cai & Ren
No full textLiangcoris Zhao, Cai & Ren, gen. nov. Type species. Liangcoris yangae Zhao, Cai & Ren, sp. nov. Diagnosis. Medium sized, oblong, smooth, shiny. Head (including neck) distinctly shorter than pronotum (Fig. 1); eyes large, protruding laterally; ocelli widely separated; anteocular portion slightly shorter than postocular portion (including neck); first antennal segment nearly as long as head (Fig. 1); rostrum robust and recurved, second segment nearly as long as first, apical segment shortest. Pronotum with anterior lobe longer than half of posterior; anterior pronotal lobe developed, longitudinal median depression short, neither reaching collar anteriorly nor transverse constriction of pronotum posteriorly (Fig. 1); posterior pronotal lobe with disk distinctly depressed, longitudinal depression, which not reaching posterior margin of pronotum (Fig. 1); lateral pronotal angles rounded, posterior margin of pronotum slightly convex, posterior angles rounded; mesopleuron without a tubercular process near border of anterior margin; scutellum nearly triangular and unarmed; femora incrassate and subapical portion constricted, fore femora thickest. Abdomen slightly dilated laterally. Distribution. China. Etymology. The new generic name refers to the shiny surface of the new species. “Liang” in Chinese means bright and shiny, and “coris” in Greek means bug. Masculine. Remarks. The body of the new genus is smooth and shiny, which is distinctly different from that of all morphologically similar genera. The general body plan and the middle longitudinal sulcus on the anterior pronotal lobe resemble those of the genus Rhynocoris, but in the new genus the first antennal segment is subequal to the head and the femora are moderately thickened (vs. in Rhynocoris, where the first antennal segment is longer than head, mid and hind femora are not distinctly incrassate). The new genus is allied to Coranus in first antennal segment subequal in length to head, but mesopleuron lacks a tubercle near border of anterior margin, the scutellum is unarmed, and legs are unnodulose in new genus (vs. the mesopleuron has a tubercle near border of anterior margin, the scutellum is armed, and legs are nodulose in Coranus). The new genus is similar to Stalireduvius: the first antennal segment is subequal in length to the head and the mesopleuron lacks a tubercle near border of anterior margin; but the new genus can be separated from the latter in legs are unnodulose (vs. the legs nodulose in Stalireduvius). These four genera can be distinguished with the following key.Published as part of Zhao, Ping, Cai, Wanzhi & Ren, Dong, 2007, Liangcoris, a new genus of Harpactorinae (Hemiptera: Reduviidae) from China, pp. 63-68 in Zootaxa 1405 on pages 63-64, DOI: 10.5281/zenodo.17548
Lin Chang and Lei Cai in a Faculty Recital
No full textThis is the program for the faculty recital featuring violinist Lin Chang and pianist Lei Cai. This recital took place on April 20, 2004, in the W. Francis McBeth Recital Hall
Rhachicephala Truong, Zhao & Cai
No full text3. Rhachicephala Truong, Zhao & Cai, gen. nov. (Figs. 25–39) Type species. Rhachicephala dilatibia Truong, Zhao & Cai, sp. nov. Diagnostic characters. Head oval, distinctly deflected downwards in front of eyes and narrowed behind eyes, with two erect long spines behind bases of antenniferous tubercles (Figs. 25, 26); first antennal segment much longer than head, second segment longest, third and fourth segments thin and short; first rostral segment subequal in length to second segment; eyes large and protruded laterally. Pronotum transversely constricted before middle; lateral pronotal angles spinously produced; prosternum anteriorly armed with two strong spines; apex of scutellum spinously produced, postscutellum with a short spine (Fig. 26). Legs moderately long; fore femur much longer than fore tibia; basal two-fifths of fore tibia dilated outwards and compressed (Figs. 25, 27– 29); mid and hind femora beneath with a short spine subapically; posterior angle of each connexival segment spinously produced. Etymology. The new generic name, Rhachicephala, alludes to two erect long spines behind the bases of the antenniferous tubercles. The words rhachi and cephala mean spine and head, respectively, in Greek. Feminine. Remarks. The new genus is similar to Petalocheirus in the anterior angles of prosternum, the collar and posterior pronotal lateral angles spinously produced, fore tibia shorter than fore femur and the head deflected in front of eyes; but in the new genus the two long spines are inserted behind the bases of the antenniferous tubercles, the basal two-fifths of the fore tibia is dilated outwards (vs. head without spine behind base of antennal tubercle and fore tibia dilated its entire length in Petalocheirus). The general body plan of the new genus resembles that of Valentia Stål, but in the new genus the postscutellum has a short spine (vs. the postscutellum without spines, and the head without spine behind base of antennal tubercle also in genus Va l e n t i a). The new genus can be distinguished from the other Vietnamese genera of the reduviid subfamily Salyavatinae with the above key.Published as part of Truong, Xuan Lam, Zhao, Ping & Cai, Wan Zhi, 2007, Notes on the subfamily Salyavatinae (Hemiptera: Reduviidae) from Vietnam, with the description of a new genus, pp. 1-20 in Zootaxa 1615 on page 9, DOI: 10.5281/zenodo.17907
Experimental studies of CAI combustion in a four-stroke GDI engine with an air-assisted injector
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.CAI combustion and the factors affecting it were intensively investigated in a single cylinder, air-assisted gasoline direct injection engine. CAI was achieved by means of residual gas trapping by utilising low-lift short duration camshafts and early closing of the exhaust valves. The effects of EVC (Exhaust Valve Closure) and IVO (Inlet Valve opening) timings, spark timing, single and split injection timings, coolant temperature, compression ratio, cam lift and duration on exhaust emissions and CAI operation were investigated experimentally. Engine speed throughout the course of the experiments, was varied from 1200rpm to 2400rpm and the air/fuel ratio was altered from stoichiometric to the misfire limit. The results show that the EVC timing, compression ratio, cam lift and duration had significant influences on CAI combustion and emissions. Early EVC when combined with higher compression ratio and higher cam lift, enhance CAI combustion operation and stability. IVO timing had minor effect on CAI combustion while spark timing hardly affects CAI operation as soon as fully-developed CAI conditions were established. Coolant temperature was revealed to have substantial impact on CAI combustion when the coolant temperature was below 65oC. The results also show the importance of injection timing. Early injection gave faster and more stable combustion, less HC and CO emissions, but more prone to knocking combustion and higher NOx emissions. Furthermore, CAI operation range could considerably be extended with injection during the recompression process. Late injection led to slower and unstable combustion, higher HC and CO emissions but lower combustion noise and NOx emissions. Split injection gave even further extension of CAI range in both stoichiometric and lean mixture operations. All the above clearly suggest, that optimising injection timing and using split injection is an effective way to control and extend CAI operation in a direct injection gasoline engine
Performance and analysis of a 4-stroke multi-cylinder gasoline engine with CAI combustion
No full textCopyright © 2002 SAE International. This paper is posted on this site with permission from SAE International. Further use of this paper is not permitted without permission from SAEControlled Auto-Ignition (CAI) combustion was realised in a production type 4-stroke 4-cylinder gasoline engine without intake charge heating or increasing compression ratio. The CAI engine operation was achieved using substantially standard components modified only in camshafts to restrict the gas exchange process
The engine could be operated with CAI combustion within a range of load (0.5 to 4 bar BMEP) and speed (1000 to 3500 rpm). Significant reductions in both specific fuel consumption and CO emissions were found. The reduction in NOx emission was more than 93% across the whole CAI range. Though unburned hydrocarbons were higher under the CAI engine operation.
In order to evaluate the potential of the CAI combustion technology, the European NEDC driving cycle vehicle simulation was carried out for two identical vehicles powered by a SI engine and a CAI/SI hybrid engine, respectively. The simulation results showed only moderate improvement in fuel economy and exhaust emissions because of low utilisation of CAI during the drive cycle.
In order to take full advantage of the CAI combustion technology, detailed analyses were carried out on the engine’s performance, heat release and combustion characteristics, emissions and the effect of gas exchange processes. These analyses showed that the engine’s performance and emissions were mainly affected by the trapped residual fractions and residual temperature. In addition, the backflow was found to affect the combustion and emission as well
Iocoris Zhao, Luo & Cai, 2009, gen. nov.
No full textIocoris gen. nov. (Figs. 1–9) Type species. Iocoris nodulifemoralis sp. nov. Diagnosis. Body elongate-oblong, abdomen moderately dilated (Figs. 1, 3). Head subequal to pronotum in length; postocular area slightly longer than anteocular; first antennal segment slightly longer than head; rostrum slender, first rostral segment exceeding anterior margin of eyes, second slightly longer than or subequal to first and third segments combined (Fig. 2). Pronotum and scutellum unarmed; collar processes undeveloped; anterior pronotal lobe feebly bulged, centrally longitudinal sulcate and subequal to half of posterior lobe in length; disk of posterior pronotal lobe feebly depressed; lateral pronotal angles rounded; posterior margin nearly straight; scutellum subtriangular, apex obtuse; legs of moderate length, femora nodulose, mid and hind femora sub-nodulose (Fig. 1); fore wing much surpassing abdominal tip, membrane area large. Abdomen posteriorly gradually dilated, posterior part of fifth segment and middle part of sixth segment of abdominal connexiva produced angulately laterally (Figs. 1, 3). Distribution. China (Yunnan). Etymology. The new generic name is named after late Prof. Chou Io (1912–2008) of Northwest A & F University in honor of his great contribution to entomology, especially to insect taxonomy of China. Masculine. Remarks. The new genus is similar to the genera Vel in us Stål and Cosmolestes Stål in the dilated abdominal connexivum and the nodulose femora, but the first antennal segment of the new genus is subequal to the head in length (Fig. 1) (vs. in the genus Velinus Stål and Cosmolestes Stål, where the first antennal segment is much longer than the head). The nodulose femora and the antennae with first segment as long as head in the new genus resemble those in the genus Stalireduvius Tomokuni & Cai, but its connexival margins is sinuate, the femur is not thickened, and the anterior pronotal lobe is subequal to half of the posterior lobe (vs. in Stalireduvius Tomokuni & Cai, the lateral margins of connexivum are roundly dilated, the femur is incrassate, and the anterior pronotal lobe is longer than half of the posterior lobe). The new genus is similar to the genus Sphedanolestes Stål in the structure of pronotum, and the head being subequal to or slightly longer than the pronotum; but it differs from the latter because the fifth and sixth abdominal connexiva are distinctly angulately produced laterally (Figs. 1, 3) (vs. in the genus Sphedanolestes the abdominal connexivum is not dilated). The new genus is similar to the genus Maldonadocoris Zhao, Yuan & Cai in the body plan and the slender rostrum, but it can be easily distinguished from the latter by the following characters: the postocular area not much longer than anteocular (Fig. 2), and the fourth and fifth abdominal connexivum is angulately produced laterally (Figs. 1, 3) (vs. in the genus Maldonadocoris the postocular area of head is posteriorly elongate, and the abdominal connexivum is not angulately dilated). Compared to the genus Biasticus Stål, Iocoris has some similar morphological characters: head subequal to pronotum in length, anterior pronotal lobe with central longitudinal sulcus, apical part of femur nodulated; but in the new genus the anteocular area is shorter than the postocular, the second rostral segment is much longer than the first segment, the first antennal segment is subequal to pronotum in length, the disk of the posterior pronotal lobe is posteriorly longitudinally depressed (vs. in the genus Biasticus the anteocular area is longer than the postocular area, the second rostral segment is a little longer than first segment, the first antennal segment is longer than pronotum, the disk of the posterior pronotal lobe is anteriorly longitudinally elevated).Published as part of Zhao, Ping, Luo, Zhaohui & Cai, Wanzhi, 2009, Iocoris nodulifemoralis, a new genus and new species of Harpactorinae (Hemiptera: Heteroptera: Reduviidae) from China, pp. 63-68 in Zootaxa 2129 on pages 63-64, DOI: 10.5281/zenodo.18832
Aulacogenia papilla Zhao & Cai, sp. nov.
No full text5. Aulacogenia papilla Zhao & Cai, sp. nov. (Figs. 31–41) Description. Color. Dark brown, suffused with irregular paler and darker markings. Eyes black; with Yshaped hairless depression on head above, longitudinal depression on pronotum, scutellum, longitudinal darker markings on hemelytron, stripes on lateral sides of mesothoracic sternum, most of metathoracic sternum, legs (except spots on femur, base of tibia, annulation subbasally on tibia or irregular paler markings on subbasal portion), posterior half of each segment of connexivum, 5 longitudinal stripes on abdomen beneath dark black; most of head beneath, paler markings on first rostral segment, carinae on pronotum grayish yellow; base of first antennal segment, apex of femur and markings on femur, base of tibia, annulation subbasally on tibia or irregular paler markings on subbasal portion, anterior half of each segment of connexivum pale yellow to dark yellow; longitudinal paler stripes and some irregular paler markings on hemelytron grayish white. Structure. Medium sized. Anteocular portion distinctly longer than postocular portion, lower margin of anteocular portion feebly concave upwards (Fig. 36); first antennal segment slightly shorter than anteocular portion, second antennal segment longer than first rostral segment; antennal tubercles corneous; inner antennal processes developed, apical part rounded, distinctly reflexed upwards; lower margin of postocular portion with 2 nodular tubercles, anterior tubercle bigger than posterior one. Anterior pronotal lobe distinctly shorter than posterior pronotal lobe, posterior portion of longitudinal depression on anterior pronotal lobe deeper; posterior pronotal lobe sublaterally with 4 longitudinal carinae, depressed portion on posterior pronotal lobe distinctly wrinkled; lateral angles of posterior pronotal lobe papillashaped (Figs. 31, 36). Middle of scutellum longitudinally depressed. Fore tibia not wider than fore femur. Posterior angle of each segment of abdomen distinctly protruding (Figs. 31, 37, 38). Measurements. ɗ. Body length 12.53, maximum width of abdomen 3.73, head length 2.20, length of anteocular part 1.07, length of postocular part 0.67, length of synthlipsis 0.60, distance between ocelli 0.33, length of antennal segments I:II:III:IV= 0.93: 1.33:?:?, length of rostral segments I:II:III= 1.05: 0.37: 0.53, length of anterior lobe of pronotum 1.00, length of posterior lobe of pronotum 1.33, maximum width of pronotum 2.62, length of scutellum 0.73, length of hemelytron 7.53. Type material. Holotype, ɗ, China, Yunnan, Xishuangbanna, Mengla, Yaoqu, 620 m, 1991 V 6, Wanzhi Cai leg., by light trap, kept in CAU. Etymology. The specific name refers to the papillashaped processes on the lateral angles of the posterior pronotal lobe. Distribution. China (Yunnan). Remarks. The new species is similar to A. vicina Miller, but in the former the antennal tubercle is longer, the inner antennal process is distinctly reflexed upwards, and the nodular tubercles on lower margin of postocular portion are larger and distinct. This species belongs to the acutangula group.Published as part of Zhao, Ping, Cai, Wanzhi & Tomokuni, Masaaki, 2005, A review of the genus Aulacogenia Stål (Heteroptera: Reduviidae: Stenopodainae) from China, pp. 23-40 in Zootaxa 1055 on pages 36-39, DOI: 10.5281/zenodo.17008
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