Bio-inspired approach for long-range underwater navigation using model predictive control

Lots of evidence has indicated that many kinds of animals can achieve goal-oriented navigation by spatial cognition and dead reckoning. The geomagnetic field (GF) is a ubiquitous cue for navigation by these animals. Inspired by the goal-oriented navigation of animals, a novel long-distance underwater geomagnetic navigation (LDUGN) method is presented in this article, which only utilizes the declination component (D) and inclination component (I) of GF for underwater navigation without any prior knowledge of the geographical location or geomagnetic map. The D and I measured by high-precision geomagnetic sensors are compared periodically with that of the destination to determine the velocity and direction in the next step. A model predictive control (MPC) algorithm with control and state constraints is proposed to achieve the control and optimization of navigation trajectory. Because the optimal control is recalculated at each sampling instant, the MPC algorithm can overcome interferences of geomagnetic daily fluctuation, geomagnetic storms, ocean current, and geomagnetic local anomaly. The simulation results validate the feasibility and accuracy of the proposed algorithm

A laboratory study on risk assessment of microcystin-RR in cropland

The persistence time and risk of microcystin-RR (MC-RR) in cropland via irrigation were investigated under laboratory conditions. In order to evaluate the efficiency of the potential adsorption and biodegradation of MC-RR in cropland and the persistence time of MC-RR for crop irrigation, high performance liquid chromatography (HPLC) was used to quantify the amount of MC-RR in solutions. Our study indicated that MC-RR could be adsorbed and biodegraded in cropland soils. MC-RR at 6.5 mg/L could be completely degraded within 6 days with a lag phase of 1 - 2 days. In the presence of humic acid, the same amount of MC-RR could be degraded within 4 days without a lag phase. Accordingly, the persistence time of MC-RR in cropland soils should be about 6 days. This result also suggested the beneficial effects of the organic fertilizer utilization for the biodegradation of MC-RR in cropland soils. Our studies also demonstrated that MC-RR at low concentration ( 100 mu g/L) significantly inhibited the growth of plants. High sensitivity of the sprouting stage plants to MC-RR treatments as well as the strong inhibitory effects resulting from prolonged irrigation further indicated that this MC-RR growth-inhibition may vary with the duration of irrigation and life stage of the plants. (c) 2007 Published by Elsevier Ltd.The persistence time and risk of microcystin-RR (MC-RR) in cropland via irrigation were investigated under laboratory conditions. In order to evaluate the efficiency of the potential adsorption and biodegradation of MC-RR in cropland and the persistence time of MC-RR for crop irrigation, high performance liquid chromatography (HPLC) was used to quantify the amount of MC-RR in solutions. Our study indicated that MC-RR could be adsorbed and biodegraded in cropland soils. MC-RR at 6.5 mg/L could be completely degraded within 6 days with a lag phase of 1 - 2 days. In the presence of humic acid, the same amount of MC-RR could be degraded within 4 days without a lag phase. Accordingly, the persistence time of MC-RR in cropland soils should be about 6 days. This result also suggested the beneficial effects of the organic fertilizer utilization for the biodegradation of MC-RR in cropland soils. Our studies also demonstrated that MC-RR at low concentration ( 100 mu g/L) significantly inhibited the growth of plants. High sensitivity of the sprouting stage plants to MC-RR treatments as well as the strong inhibitory effects resulting from prolonged irrigation further indicated that this MC-RR growth-inhibition may vary with the duration of irrigation and life stage of the plants. (c) 2007 Published by Elsevier Ltd

Analysis of Innovative Structural Design of Liyutuo Lounge Bridge in Dujiangyan

U projektu mosta Liyutuo Lounge višekatna okvirna konstrukcija kombinirana je s masivnom konstrukcijom mosta, te je tako projektirana jedinstvena građevina dvostruke namjene. Prometni dio rasponske konstrukcije mosta je prednapeti kruti betonski okvir, kruto spojen sa stupom, nosačem i poprečnim nosačem koji se odlikuju tipičnim značajkama prednapete betonske konstrukcije i okvirne konstrukcije. Pri projektiranju temelja stupa, primjenjeno je naknadno injektiranje te kombinacija uzdužnih veznih greda kako bi se riješili problemi malog promjera pilota i velikog opterećenja.According to its design, the Liyutuo Lounge Bridge combines a multilayer frame structure with a large bridge structure, offering a solution involving a unique dual-use structure. The transport layer of the superstructure is a prestressed concrete rigid frame, and the pier, girder, and cross girder, are rigidly connected, and have typical characteristics of a prestressed concrete bridge structure and frame structure. For the structural design of pier foundations, the post-grouting and a combination of longitudinal tie beams are used to solve the challenges associated with a small pile diameter and large loads

Effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts under experimental conditions

Soil cyanobacterial crusts occur throughout the world, especially in the semiarid and arid regions. It always encounters sand burial, which is an important feature of mobile sand dunes. A greenhouse 41 study was conducted to determine the effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts in six periods of time (0, 5, 10, 15, 20 and 30 d after burying) and at five depths (0, 0.2, 0.5, 1 and 2cm). The results indicated that with the increase of the burial time and burial depth extracellular polysaccharides content and Fv/Fm decreased correspondingly and there were no significant differences between 20 and 30 burial days under different burial depths. The degradation of chlorophyll a content appeared only at 20 and 30 burial days and there was also no significant difference between them under different burial depths. It was also observed a simultaneous decrease of the values of the Fv/Fm and the content of extracellular polysaccharides happened in the crusted cyanobacterium Microcoleus vaginatus Gom. It may suggest that there exists a relationship between extracellular polysaccharides and recovery of the activity of photosystem II (PS II) after rehydration.Soil cyanobacterial crusts occur throughout the world, especially in the semiarid and arid regions. It always encounters sand burial, which is an important feature of mobile sand dunes. A greenhouse 41 study was conducted to determine the effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts in six periods of time (0, 5, 10, 15, 20 and 30 d after burying) and at five depths (0, 0.2, 0.5, 1 and 2cm). The results indicated that with the increase of the burial time and burial depth extracellular polysaccharides content and Fv/Fm decreased correspondingly and there were no significant differences between 20 and 30 burial days under different burial depths. The degradation of chlorophyll a content appeared only at 20 and 30 burial days and there was also no significant difference between them under different burial depths. It was also observed a simultaneous decrease of the values of the Fv/Fm and the content of extracellular polysaccharides happened in the crusted cyanobacterium Microcoleus vaginatus Gom. It may suggest that there exists a relationship between extracellular polysaccharides and recovery of the activity of photosystem II (PS II) after rehydration

The comparison of phosphorus pools from the sediment in two bays of Lake Dianchi for cyanobacterial bloom assessment

The different pools in the sediment from two bays with different scales of cyanobacterial bloom were studied to assess the trophic status. With large scale of cyanobacterial bloom in Haigeng bay the concentrations of different phosphorus fractions were higher than the corresponding concentrations in Macun bay, and especially WSP and AAP are the most evident, which indicates that there are more available and potential available phosphorus in Haigeng bay. The adsorption experiment also shows that the sediment in Haigeng bay is more saturated than that in Macun bay. Haigeng bay can be faced with the more serious ecological danger. Furthermore the death and deposit of a mass of algae can contribute to phosphorus released from sediment and help to the breakout of newborn cyanobacterial blooms

EFFECTS OF TEMPERATURE, LIGHT, NITRATE AND AMMONIUM ON GROWTH AND PHOTOSYNTHESIS OF MICROCYSTIS AERUGINOSA (CYANOBACTERIA) UNDER IRON-LIMITED AND IRON-REPLETE CONDITIONS

Little is known about interactions of iron with temperature, light, nitrate and ammonium on physiology of the freshwater species Microcystis aeruginosa (Cyanobacteria). Results showed that growth and photosynthesis of M aeruginosa were inhibited by Fe limitation in all cultures beside nitrogen-treatment groups. Relatively low or high temperature and light intensity could impair the growth and photosynthesis of M aeruginosa despite Fe concentration in media. Under Fe-replete conditions, both the OD665 and chlorophyll a reached peaks at 30 degrees C and light intensity of 30 mu mol photons m(-2) s(-1). Nitrate is proven to be the main nitrogen source for growth of M. aeruginosa collected from Lake Dianchi. Yield, ETRmax, alpha and I-k also reached highest values at light intensity of 30 mu mol photons m(-2) s(-1) and high FeNO3- conditions, but at a temperature of 20 degrees C. Our results can be used to help control blooms of M. aeruginosa in Lake Dianchi and other water-bodies