172,679 research outputs found
Automated Design of Lightweight Exploration Rovers
No full textIn the recent years, vehicle-environment modeling techniques and powerful simulation tools have been used exhaustively to design wheeled rovers. In spite of that, rover preliminary design is still very dependent on human designer. It is also wellknown that human analysis of a complex vehicle dynamics is very time consuming, which implies in a simplified analysis of just a few useful operating conditions. It compels strict achievement of requirements without a deeper investigation of performance optimization potential during preliminary design phase. Our in-house developed rover optimization tool allow us to achieve a reasonable configuration having mobility and locomotion requirements and a given suspension concept as inputs. It reduced drastically the time usually devoted to synthesize some rover parametric configuration. We show the result of an optimized ExoMars rover under our scenario-oriented multi-objective optimization concept. The results are assessed through parameter variation studies to evaluate: allowable volume to place the center of mass of the vehicle, sensitivity analysis, Pareto frontier relating important metrics two by two, and figures of merit illustrating mapping of the design parameters into the criteria space. This research generates two branches of special interest: applicability of the current results (other than straight forward construction of the obtained suspension); and further development of the optimization
tool. The current results can be applied to the selection of candidate actuator designs for example. It can be done by
observation of the torque profiles of the vehicle's wheels as the vehicle drives on complex terrain in a simulation. This is used to evaluate candidate actuator design concepts which make the vehicle faster but at the same time do not enforce it to underperform in critical scenarios. Currently, our tool is able to perform geometric configuration optimization. But the results have shown that performance improvement is still possible according to the design of wheels, bogies and their mechanical connections (suspension). Optimization of locomotion components individually (e.g. topology optimization) and suspension
concept synthesis are also discussed as means to enhance performance. Strategies still have to be investigated in order to define connection constraints in a suspension concept synthesis. This work summarizes results of a four-year research, but it can also be considered as the beginning of a second major step in the development of a fully automatized scenario-oriented
tool to achieve complete rover synthesis including suspension concept synthesis, geometric configuration optimization, and component optimization
Effects of single injection of carp pituitary extract and human chorionic gonadotropin on germinal vesicle migration and ovulation in lampan sungai, Puntius schwanenfeldii (Bleeker): A preliminary study
No full textThe effects of crude pituitary extract (CPE) and human chorionic gonadotropin (hCG) on germinal vesicle migration and ovulation in lampan sungai Puntius schwanenfeldii (Bleeker) were investigated. Sexually mature female lampan sungai were divided into four groups (n=3 per group). In both experiments, fish were injected intramuscularly (im) once and were checked for germinal vesicle migration and sign of ovulation 8 h following injection. In experiment 1, females were treated with CPE at doses of 2, 4, or 6 mg/kg body weight (BW) while controls were administered an equivalent volume of saline. Ovulation occurred in one fish given 2 mg/kg and in another fish that received 6 mg/kg CPE. In a second experiment, female fish were administered hCG at doses of 1000, 2000, or 4000 IU/kg body weight. Similarly, controls received only saline. One female injected with 4000 IU/kg hCG responded positively to the hormone treatment. Clearly, in our study, a single intramuscular injection of CPE and hCG induced spawning in lampan sungai as well as accelerated oocyte development as evidenced by the increasing percentage of oocytes showing germinal vesicle migration
Kinematics-based velocity estimation of lunar rovers
No full textWheeled mobile robots are increasingly being utilized in unknown and dangerous situations such as lunar surface exploration. Velocity estimation is of importance for lunar rovers to autonomously navigate and successfully traverse on rough terrains. The dynamic effects occurring at the wheel-terrain interface such as wheel slips make it difficult to real-time estimate the rover's velocity only by position-measurement sensors. Effective acceleration sensor data are hard to observe since lunar rovers usually move at a very slow speed. This paper proposes a kinematics-based method for velocity estimation of lunar rovers by using wheel encoders and gyro measurements. Treating the lunar rover with passively compliant mechanisms as a series-parallel multi-body system, we can directly build the whole kinematics model based on closed velocity chain theory. The wheel-terrain physical contact and wheel slips involving rolling slip, side slip and turning slip are also investigated. The forward velocity calculation is achieved based on solving kinematics of the rover. Low-accuracy gyro signals are modelled as a stochastic procedure and processed with the standard Kalman filter. Physical experimental results of gyro signals filtering and velocity estimation are given to show the validity and usefulness of the methods. This kinematics-based velocity estimation method can be easily performed based on on-board sensors with low system cost
Cheilodipterus singapurensis Bleeker 1860
No full textCheilodipterus singapurensis Bleeker, 1860 Cheilodipterus singapurensis Bleeker, 1860c, is based on a specimen which was related to a coloured painting by Castelnau, No. 67 (Fig. 4), with notes “ Cheilodipterus singaporensis Cast. Blk octovittatus Cu? Val nov. spec.”. The mouth is partly open and shows large teeth. In the original Latin description, Bleeker (1860c) lists a single specimen of 149 mm total length (TL) and in the Dutch remarks he refers to another specimen of 119 mm TL. By 1874 Bleeker had added three more specimens and modified his description. A figure was provided by Bleeker (1875 – 1876 b: Pl. 35) in the Atlas. No changes were made to the description or remarks in 1876 from the additions in 1874. The descriptions by Bleeker, his figure and Castelnau’s painting do not show a black mark in the area of the anal and genital openings. Bleeker’s (1875 – 1876) figure was based on the juvenile colour pattern, probably from one of the smaller specimens. Gon (1993) provided the most recent revision of Cheilodipterus and recognized C. singapurensis as a valid species. Although Gon listed Bleeker’s material, RMNH 5619 with three specimens, no types are mentioned or discussed. Ernest A. Lachner examined Bleeker’s material in 1956. He recorded four specimens present, one with a “conspicuously dark vent” (Lachner original notes). Four specimens were present when Fraser examined the lot in 1972. The largest specimen in the lot is about 144 mm TL not 149 mm. Martin Boeseman (in litt.) suggested that Bleeker may have made a 5 mm error reading his ruler, the printer misread a 9 for a 3, or the holotype was in the second lot of the Auction Catalog and went elsewhere, or is lost. We regard the largest specimen as the probable holotype and one of the two smaller specimens mentioned by Bleeker is a paratype. The third specimen has no type status. No Bleeker specimen has been reported at the British Museum, another possible repository for the specimen. The specimen with the dark vent was identified as Cheilodipterus truncatus (139 mm TL) and removed to RMNH 26674 in 1972. While there are two interpretations of the significance of the blackish vent (Lachner, 1953; Gon 1993), neither Bleeker’s written descriptions nor Castelnau’s figure provide any evidence that they observed this colour pattern. We conclude that Castelnau’s figure of an adult was used appropriately by Bleeker.Published as part of Russell, Barry C., Fraser, Thomas H. & Larson, Helen K., 2010, Castelnau'S Collection Of Singapore Fishes Described By Pieter Bleeker, pp. 93-102 in Raffles Bulletin of Zoology 58 (1) on page 95, DOI: 10.5281/zenodo.534243
FIGURE 7. Anthias aplodactylus Bleeker, 1858 in Taxonomy of the genus Dactylanthias Bleeker (Teleostei: Serranidae: Anthiadinae)
No full textFIGURE 7. Anthias aplodactylus Bleeker, 1858, holotype, RMNH 5457, 170 mm SL. Photo by E. Dundorp.Published as part of Pogonoski, John J. & Gill, Anthony C., 2021, Taxonomy of the genus Dactylanthias Bleeker (Teleostei: Serranidae: Anthiadinae), pp. 417-430 in Zootaxa 4926 (3) on page 424, DOI: 10.11646/zootaxa.4926.3.6, http://zenodo.org/record/452941
Response assessment after neoadjuvant therapy in esophageal cancer : towards personalized treatment
No full textContains fulltext :
230646.pdf (Publisher’s version ) (Open Access)Radboud University, 09 maart 2021Promotores : Rosman, C., Rovers, M.M. Co-promotores : Klarenbeek, B.R., Post, R.S. van der175 p
Enchelycore schismatorhynchus Bleeker 1853
No full textEnchelycore schismatorhynchus (Bleeker, 1853) RdWdR Muraena schismatorhynchus Bleeker, 1853 c: 301 (type locality: Bengkulu, Sumatra, Indonesia, eastern Indian Ocean). Enchelycore schismatorhynchus (Bleeker, 1853 c): Shen et al., 1993: 101, fig. 15 - 6, 7; Chen et al., 1994: 48; Chen, 2004: 27; Loh et al., in press:table 1. Gymnothorax schismatorhynchus (Bleeker, 1853 c): Chen & Yu, 1986: 247. Remarks. A common species found in the coral reef regions of southern Taiwan.Published as part of Ho, Hsuan-Ching, Smith, David G., Mccosker, John E., Hibino, Yusuke, Loh, Kar-Hoe, Tighe, Kenneth A. & Shao, Kwang-Tsao, 2015, Annotated checklist of eels (orders Anguilliformes and Saccopharyngiformes) from Taiwan, pp. 140-189 in Zootaxa 4060 (1) on pages 153-154, DOI: 10.11646/zootaxa.4060.1.16, http://zenodo.org/record/24365
On multi-objective optimization of planetary exploration rovers applied to ExoMars-type rovers
No full textExoMars is the first robotic mission of the Aurora program of the European Space Agency (EAS). Surface mobility (as provided by ExoMarks rover) is one of the enabling technologies necessary for future exploration missions. This work uses previouly developed mathematical models to represent an ExoMars rover operation in soft/rocky terrain. The models are used in an optimization loop to evaluate multiple objective functions affected by the change in geometrical design parameters. Several objective funktions can be used in our optimization environment powered by MOPS (Multi-Objective Parameter Synthesis). Two environments are used to simulate the rover in stability sensitive conditions and power and sinkage sensitive conditions. Finally, an ExoMars-like configuration is proposed and consistent improvemnt directions are pointed out
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