Prioritized Planning for Target-Oriented Manipulation via Hierarchical Stacking Relationship Prediction

In scenarios involving the grasping of multiple targets, the learning of stacking relationships between objects is fundamental for robots to execute safely and efficiently. However, current methods lack subdivision for the hierarchy of stacking relationship types. In scenes where objects are mostly stacked in an orderly manner, they are incapable of performing human-like and high-efficient grasping decisions. This paper proposes a perception-planning method to distinguish different stacking types between objects and generate prioritized manipulation order decisions based on given target designations. We utilize a Hierarchical Stacking Relationship Network (HSRN) to discriminate the hierarchy of stacking and generate a refined Stacking Relationship Tree (SRT) for relationship description. Considering that objects with high stacking stability can be grasped together if necessary, we introduce an elaborate decision-making planner based on the Partially Observable Markov Decision Process (POMDP), which leverages observations and generates the least grasp-consuming decision chain with robustness and is suitable for simultaneously specifying multiple targets. To verify our work, we set the scene to the dining table and augment the REGRAD dataset with a set of common tableware models for network training. Experiments show that our method effectively generates grasping decisions that conform to human requirements, and improves the implementation efficiency compared with existing methods on the basis of guaranteeing the success rate.Comment: 8 pages, 8 figure

Different Soil Particle-Size Classification Systems for Calculating Volume Fractal Dimension—A Case Study of Pinus sylvestris var. Mongolica in Mu Us Sandy Land, China

Characterizing changes in the soil particle-size distributions (PSD) are a major issue in environmental research because it has a great impact on soil properties, soil management, and desertification. To date, the use of soil volume fractal dimension (D) is a feasible approach to describe PSD, and its calculation is mainly dependent on subdivisions of clay, silt, sand fractions as well as different soil particle-size classification (PSC) systems. But few studies have developed appropriate research works on how PSC systems affect the calculations of D. Therefore, in this study, topsoil (0–5 cm) across nine forest density gradients of Pinus sylvestris var. mongolica plantations (MPPs) ranging from 900–2700 trees ha–1 were selected in the Mu Us sandy land, China. The D of soil was calculated by measuring soil PSD through fractal model and laser diffraction technique. The experimental results showed that: (1) The predominant PSD was distributed within the sand classification followed by clay and silt particle contents, which were far less prevalent in the study area. The general order of D values (Ds) was USDA (1993) > ISO14688 (2002) > ISSS (1929) > Katschinski (1957) > China (1987) > Blott & Pye (2012) PSC systems. (2) Ds were significantly positively related to the contents of clay and silt, and Ds were significantly negatively to the sand content. Ds were susceptible to the MPPs establishment and forest densities. (3) Ds of six PSC systems were significantly positive correlated, which indicated that they not only have difference, but also have close connection. (4) According to the fractal model and descriptions of soil fractions under different PSC systems, refining scales of clay and sand fractions could increase Ds, while the refining scale of silt fraction could decrease Ds. From the conclusions above, it is highly recommended that USDA (1993) and Blott & Pye (2012) PSC systems be used as reliable and practical PSC systems for describing and calculating D of soil PSD

PyunBBX18 Is Involved in the Regulation of Anthocyanins Biosynthesis under UV-B Stress

(1) Background: Populus yunnanensis Dode (P. yunnanensis) grows in the low-latitude and high-altitude areas of southwest China. In low-latitude and high-altitude areas, plants suffer from the high intensity of UV-B (ultraviolet-b) radiation, and they have a complete regulation system to adapt to the environment of the high UV-B radiation. As natural antioxidants, anthocyanins play an important role in scavenging free radicals. BBX (B-box) genes are involved in anthocyanins biosynthesis. (2) Methods: By exploring the gene structure and motifs of PyunBBX genes (genes of P. yunnanensis BBX family) and the evolutionary relationship between PyunBBX genes and other species BBX genes, six PyunBBX genes that responded to UV-B and participated in anthocyanins biosynthesis were screened. BBX, with the potential to regulate anthocyanins biosynthesis, was further investigated by anthocyanins content determination and RT-qPCR (real-time quantitative polymerase chain reaction); (3) Results: After 7 days of UV-B treatment, anthocyanins were significantly accumulated, and the expression of PyunBBX18 was up-regulated for 7 days. The expression of PyunBBX12 was inhibited by UV-B treatment. By analyzing the RNA-seq data of leaves and bark of P. yunnanensis, we found that PyunBBX18 was highly expressed in leaves and young bark; (4) Conclusions: These results showed that PyunBBX18 and PyunBBX12 may be involved in the response process of UV-B stress, in which PyunBBX18 may regulate the anthocyanins biosynthesis to resist UV damage

Identification of Reliable Reference Genes under Different Stresses and in Different Tissues of <i>Toxicodendron succedaneum</i>

Toxicodendron succedaneum (L.) Kuntze (T. succedaneum) is an economic tree species that produces urushiol and urushi wax, and it is of great value in industry and medicine. However, the stability of reference genes (RGs) has not been systematically reported in T. succedaneum to date. In this study, the expression of 10 candidate RGs was analyzed by RT-qPCR in different tissues (roots, stems, leaves), stress treatments (high/low temperature, drought), and hormone stimulation (jasmonic acid, JA). Then, the stability ranking of 10 candidate genes was evaluated by ∆Ct analysis and three software programs: geNorm, NormFinder, and BestKeeper. Finally, RefFinder was used to comprehensively analyze the expression stability of 10 candidate genes. The comprehensive analysis showed that TsRG05/06, TsRG01/06, and TsRG03/ACT were stable under high/low-temperature stress, drought stress, and JA treatment, respectively. TsRG03 and ACT had stable expression in different tissues. While the TsRG03 and ACT were recommended as the suitable RGs for T. succedaneum in all samples. Meanwhile, UBQ was the least suitable as a reference gene for T. succedaneum. In addition, the results of geNorm showed that the combination of two stable RGs could make the results of gene expression more accurate. These results provide alternative RGs for the study of gene function, correction, and normalization of target gene expression and directed molecular breeding in T. succedaneum

River Ecosystem Health Assessment Using a Combination Weighting Method: A Case Study of Beijing Section of Yongding River in China

(1) Background: River health assessment provides the foundation for sustainable river development and management. However, existing assessments have no uniform standards and methods. (2) Methods: The combination weighting method was proposed, drawing on the advantages of subjective and objective weighting methods. To comprehensively investigate the river health level, an index system based on 16 indices selected from river morphology, river water environment, riparian condition, and social services level was established. The method and framework were applied to the Beijing section of Yongding River in China. (3) Results: The comprehensive weights of river morphology, river water environment, riparian condition, and social services are 0.1614, 0.3170, 0.4459, and 0.0757, respectively. The river health comprehensive index of Yongding River is 3.805; the percentages of excellent, healthy, sub-healthy, unhealthy, and sick river segments are 0%, 11%, 69%, 20%, and 0%, respectively. (4) Conclusions: The results indicate that Yongding River is in a sub-healthy state, and the riparian condition is the key factor that affects the river ecosystem health. Health level exhibited a remarkable spatial variation, mainly influenced by anthropogenic activities, and effective measures are needed to minimize the impact in fragile ecological areas

Enlargement of uniform micropores in hierarchically ordered micro-mesoporous carbon for high level decontamination of bisphenol A

In this work we prepared hierarchically ordered micro-mesoporous carbon with enlarged uniform micropores, specifically tailored for the high level adsorption of environmental pollutant bisphenol A (BPA). Sizes of both the primary micropore (1.3 nm) and the primary mesopore (9.0 nm) could be tuned by controlling the condensation behavior of phloroglucinol-terephthalaldehyde resin in a tri-constituent system based on evaporation induced self-assembly. As a result of this the special structure was able to develop high surface area (623-1985 m2 g-1) and large pore volume (0.7-2.3 cm 3 g-1). By tuning the micropore size to accommodate the molecular dimensions of BPA, an ultra-high adsorption capacity of 1106 mg g -1 was achieved, three times higher than previously reported values. Kinetic studies revealed that high pore interconnectivity and micropore accessibility were the key to unrestricted adsorbate diffusion through the pore channels and the subsequent high level adsorption. This development sheds new light on the importance of the carbon source in the control of pore size in carbons. The materials hold great potential for application in the purification of industrial process water with high level BPA contamination

Synthesis of bismuth nanoparticles and self-assembled nanobelts by a simple aqueous route in basic solution

An aqueous reduction method was successfully used to prepare Bi nanoparticles at 90 degrees C with bismuth nitrate pentahydrate [Bi(NO3)(3).5H(2)O] and sodium-hypophosphite (NaH2PO2.H2O) as reactants. The diameters of Bi nanoparticles were controlled in the range of 10-50 nm under varied experimental parameters. And Bi nanobelts can also be constructed through self-assembly of Bi nanoparticles, which had typical lengths of up to 10 mu m and widths of up to 100 nm. Tartaric acid (TA, H2C4H4O6) and NaOH are key factors in our preparation. These Bi nanostructures are expected to find potential applications in a variety of areas due to their optical characteristics. Various techniques such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to characterize the obtained nanostructures. (C) 2011 Elsevier B.V. All rights reserved