Perception‐aware autonomous mast motion planning for planetary exploration rovers

Highly accurate real‐time localization is of fundamental importance for the safety and efficiency of planetary rovers exploring the surface of Mars. Mars rover operations rely on vision‐based systems to avoid hazards as well as plan safe routes. However, vision‐based systems operate on the assumption that sufficient visual texture is visible in the scene. This poses a challenge for vision‐based navigation on Mars where regions lacking visual texture are prevalent. To overcome this, we make use of the ability of the rover to actively steer the visual sensor to improve fault tolerance and maximize the perception performance. This paper answers the question of where and when to look by presenting a method for predicting the sensor trajectory that maximizes the localization performance of the rover. This is accomplished by an online assessment of possible trajectories using synthetic, future camera views created from previous observations of the scene. The proposed trajectories are quantified and chosen based on the expected localization performance. In this study, we validate the proposed method in field experiments at the Jet Propulsion Laboratory (JPL) Mars Yard. Furthermore, multiple performance metrics are identified and evaluated for reducing the overall runtime of the algorithm. We show how actively steering the perception system increases the localization accuracy compared with traditional fixed‐sensor configurations.     

Seismic Earth Pressure Exerted on Retaining Walls Under a Large Seismic Load

In recent years, serious damage has been done to retaining structures because of large earthquakes. In order to establish practical methods for evaluating the seismic earth pressure, which is one of the important external forces acting on retaining structures during large earthquakes, a series of shaking table tests was conducted on retaining wall (RW) models. The experiments revealed that the seismic active earth pressure was considerably smaller than that obtained by the Mononobe-Okabe theory, particularly under a large seismic load. Furthermore, it was demonstrated that the seismic earth pressure had an upper limit, which was determined by the force equilibrium of the soil wedge at the critical state when the RW lost its stability. On the basis of the test results, a new method to evaluate the seismic earth pressure for practical designs under a large seismic load has been suggested. This proposed method provides a reasonable earth pressure as well as an angle of failure plane, those of which depend on the seismic stability of the retaining wall. It has been confirmed that earth pressure obtained by the proposed method agrees well with the measured seismic earth pressure exerted on several retaining walls with different degrees of stability.     

A Dietary Oxysterol, 7-Ketocholesterol,Exacerbates Imiquimod-Induced Psoriasis-like Dermatitis in Steatohepatitic Mice

Patients with psoriasis are at a higher risk of developing nonalcoholic fatty liver disease. We previously identified an oxidized derivative of cholesterol, 7-ketocholesterol (7KC), in diet-induced steatohepatitic mice. Here, we investigated whether 7KC exacerbates psoriasis-like dermatitis by accelerating steatohepatitis in mice. A high-fat/high-cholesterol/high-sucrose/bile salt diet (nonalcoholic steatohepatitis (NASH) diet) with or without 0.0125% 7KC was fed to C57BL/6 mice (7KC or control group) for three weeks to induce steatohepatitis. A 5% imiquimod cream was then applied to the ears and dorsal skin for four days to induce psoriasis-like dermatitis. Hepatic lipid accumulation and inflammatory cell infiltration were exacerbated in the 7KC group compared with the control group after three weeks. Serum tumor necrosis factor-α (TNF-α) levels were also elevated in the 7KC group (108.5 ± 9.8 vs. 83.1 ± 13.1 pg/mL, p < 0.005). Imiquimod cream increased the psoriasis area severity index (PASI) score in mice in the 7KC group (9.14 ± 0.75 vs. 5.17 ± 1.17, p < 0.0001). Additionally, Tnfa, Il23a, Il17a, and Il22 mRNA levels in the dorsal lesion were significantly upregulated. Finally, Th17 cell differentiation and the TNF signaling pathway were enhanced in the dorsal lesions and liver of mice in the 7KC group. These data suggest that steatohepatitis and psoriasis are linked by a potent, diet-related factor.     

Radiation measurements in large-scale kerosene pool flames using high-speed thermography

Details of apparent temperature distributions in large-scale kerosene pool flames in a 2.7 m square tank were measured by high-speed thermography which stores a thermal image in the form of a thermal TV color image with 25,600 data points every 0.1 second. The apparent temperature image can be changed to irradiance by simple approximations. The irradiance of the data (4 cases and 280 images) was compared with that of a wide-angle thermopile radiometer to verify the data from the thermography. A series of data recorded at intervals of one and five seconds was also analyzed to obtain the radiance distribution in the flame. The analysis allows the following conclusions: Irradiance values obtained by high-speed thermography are not very different from those of a conventional wide-angle thermopile radiometer. The high radiance zone, which ordinary cameras do not show, was determined by the average value of each of 70 apparent temperature images, and the center of the high radiance zone is located at about 0.3 D (D is the tank diameter). The moderately high apparent temperature range of 1232K–1448K apparently has a strong influence on the irradiance of pool flames.     

Control strategy for a distributed DC power system with renewable energy

This paper deals with a DC-micro-grid with renewable energy. The proposed method is composed of a gearless wind power generation system, a battery, and DC loads in a DC distribution system. The battery helps to avoid the DC over-voltages by absorbing the power of the permanent magnet synchronous generator (PMSG) during line-fault. In addition, the control schemes presented in this paper including the maximum power point tracking (MPPT) control and a pitch angle control for the gearless wind turbine generator. By means of the proposed method, high-reliable power can be supplied to the DC distribution system during the line-fault and stable power supply from the PMSG can be achieved after line-fault clearing. The effectiveness of the proposed method is examined in a MATLAB/Simulink^® environment.     

Accumulation of Misfolded Protein Aggregates Leads to the Formation of Russell Body-like Dilated Endoplasmic Reticulum in Yeast

RNAP-I, an aspartic proteinase from a filamentous fungus Rhizopus niveus, is secreted very efficiently in Saccharomyces cerevisiae. It is synthesized first as a precursor form with signal sequence and prosequence in its amino-terminus. Our previous study indicated that the prosequence of RNAP-I had important roles in its correct folding and secretion in yeast, and that a prosequence-deleted derivative of RNAP-I, Δpro, was not secreted but was retained and degraded in the yeast endoplasmic reticulum (ER). In the present study, we show that the accumulation of Δpro in the yeast ER caused elevated synthesis of ER resident chaperones, indicating that Δpro is recognized as an unfolded protein species in the ER. Our biochemical data demonstrated that Δpro formed aggregates which contained BiP, but not protein disulfide isomerase (PDI), in the ER. Immunoelectron microscopical analysis revealed that the Δpro aggregates were indeed visible as electron-dense regions in the ER and nuclear envelope. Such ‘chaperone-associated misfolded protein bodies’ were observed for the first time in yeast. Morphologies of the ER and nucleus were drastically altered by the accumulation of the Δpro aggregates. The ER lost its flat cisternal shape; the ER lumen extended aberrantly and the ER membrane irregularly proliferated. The misfolded Δpro proteins are probably sorted from the ordinary ER lumen to form the aggregates so that the ER function would not be grossly impaired, and the dilated ER may represent an ER subcompartment where the Δpro aggregates are degraded. © 1997 by John Wiley & Sons, Ltd.     

Substitution effect on metal-insulator transition in Cu(Ir1−xMx)2S4 (M = Sn, Hf)

A spinel CuIr₂S₄ exhibits a temperature-induced metal-insulator (M-I) transition at around 226 K. Non-magnetic substitution effect on the M-I transition, T_M-I, in Cu(Ir_1−xM_x)₂S₄ (M = Sn, Hf) has been studied on the focus of the rather low composition region of x. Magnetic property of Cu(Ir_1−xM_x)₂S₄ (M = Sn, Hf) has been examined experimentally. The T_M-I decreases with increasing x and the temperature hysteresis becomes unclear within the experimental errors. The step anomaly in the magnetic susceptibility smears out and the T_M-I becomes ill defined around x = 0.20 in Cu(Ir_1−xSn_x)₂S₄, and x = 0.10 in Cu(Ir_1−xHf_x)₂S₄, respectively. These substitutions play an important role in decoupling the spin-dimerization of Ir⁴⁺-Ir⁴⁺ in CuIr₂S₄, and lead the destruction of the metal-insulator transition.     

Tomakomai Large Scale Crude Oil Fire Experiments

This paper summarizes the results of large-scale crude oil fire experiments conducted in Tomakomai, Japan, in 1998 to obtain information that could be applied to the development of firefighting strategies for, and the design of, huge petroleum storages. Arabian light-equivalent crude oil was burned in pans 5-, 10-, and 20-m in diameter. Most of the experiments were performed under favorable conditions. Measured data include external radiation, infrared image of the flame, flame temperature, gas concentration inside the flame, and other burning characteristics. The height of the strongest radiant emittance was H/D=0.1 to 0.2, where D=pan diameter and H=height from the initial fuel surface, and a kind of fireball appeared occasionally at the intermittant flame zone. Emitted smoke particles were sampled on the ground and observed with a scanning electron micrograph, and the distribution of the diameters of primary smoke particles was examined. The average diameter of primary smoke particles is 53.0 (±10.5)nm. The dependence of burning characteristics and flame structure on pan diameter is discussed. The flame height of the 20-m diameter pan fire is 1.9 (±0.3) D. The burning rate increases as the pan diameters increase, but the radiative fraction decreases as pan diameter increases.     

Influence of refraction on the visual field defects in normal tension glaucoma and primary open angle glaucoma eyes

The prevalence of normal tension glaucoma (NTG) or primary open angle glaucoma (POAG) is higher in myopic populations and the prevalence of myopia and NTG is relatively high in the Japanese. To evaluate the influence of myopic refractive error on the central visual field defect in NTG eyes, the data obtained from NTG eyes with the Humphrey Visual Field Analyser were analysed in comparison with those from POAG eyes. One hundred and twenty NTG eyes and one hundred and ninety-seven POAG eyes were included. All of them had clear ocular media, but no myopic degeneration in the fundus. Multiple linear regression analysis was performed with a dependent variable of the deviation of the measured threshold value from normal reference value (total deviation, STATPAC) and independent variables of refractive error and mean deviation (STATPAC). Myopic power was found to be positively correlated with the depression in the lower papillo-macular area in both NTG and POAG eyes, and it was negatively correlated with the depression in an upper arcuate area extending just nasal to the fixation only in NTG eyes.