A novel integrated method of detection-grasping for specific object based on the box coordinate matching

To better care for the elderly and disabled, it is essential for service robots to have an effective fusion method of object detection and grasp estimation. However, limited research has been observed on the combination of object detection and grasp estimation. To overcome this technical difficulty, a novel integrated method of detection-grasping for specific object based on the box coordinate matching is proposed in this paper. Firstly, the SOLOv2 instance segmentation model is improved by adding channel attention module (CAM) and spatial attention module (SAM). Then, the atrous spatial pyramid pooling (ASPP) and CAM are added to the generative residual convolutional neural network (GR-CNN) model to optimize grasp estimation. Furthermore, a detection-grasping integrated algorithm based on box coordinate matching (DG-BCM) is proposed to obtain the fusion model of object detection and grasp estimation. For verification, experiments on object detection and grasp estimation are conducted separately to verify the superiority of improved models. Additionally, grasping tasks for several specific objects are implemented on a simulation platform, demonstrating the feasibility and effectiveness of DG-BCM algorithm proposed in this paper

The Efficiency of the Chinese Prefabricated Building Industry and Its Influencing Factors: An Empirical Study

China is a world leader in capital construction. In the construction field, the shift toward prefabricated construction has become an important path for industrial transformation. This paper refers to the development of the prefabricated building industry in China, and uses input and output perspectives to examine its efficiency. It builds a data envelopment analysis model to evaluate the efficiency of the prefabricated building industry in China at both the micro and macro levels, and uses the Tobit model to empirically analyze the factors that influence this industry’s efficiency. It finds that the country’s prefabricated building industry has a moderate micro-level efficiency. This means that it is necessary to further rationalize industrial planning; strengthen technological innovation; and improve standardization, mechanization, and automation levels. At the macro level, China’s prefabricated buildings have a low industrial efficiency and remain at the initial stage of industrial development. A series of problems, such as small industrial scale and unsound policies, are restricting the industry’s rapid and efficient development. We propose several countermeasures and suggestions for the (micro- and macro-level) sustainable development of the prefabricated building industry in China, and anticipate that this will have implications for this industry’s worldwide development

Model Test of the Reinforcement of Surface Soil by Plant Roots under the Influence of Precipitation

We present the results of the reinforcement of plant root systems in surface soil in a model test to simulate actual precipitation conditions. In the test, Eleusine indica was selected as herbage to reinforce the soil. Based on the various moisture contents of plant roots in a pull-out test, a fitting formula describing the interfacial friction strength between the roots and soil and soil moisture content was obtained to explain the amount of slippage of the side slope during the process of rainfall. The experimental results showed that the root systems of plants successfully reinforced soil and stabilized the water content in the surface soil of a slope and that the occurrence time of landslides was delayed significantly in the grass-planting slope model. After the simulated rainfall started, the reinforcement effect of the plant roots changed. As the rainfall increased, the interfacial friction between the roots and the soil exhibited a negative power function relationship with the water content. These conclusions can be used as a reference for the design of plant slope protection and reinforcement

Ion acoustic quasi-soliton in an electron-positron-ion plasma with superthermal electrons and positrons

In this work, we are concerned with the ion acoustic quasi-soliton in an electron-positron-ion plasma with superthermal electrons and positrons. By using the reductive perturbation method, the Korteweg-de Vries equation is derived from the governing equations of ion acoustic waves. An interesting soliton-cnoidal wave solution of the Korteweg-de Vries equation and its quasi-soliton behaviour are presented. The influence of electron superthermality, positron superthermality and positron concentration ratio on characteristics of the quasi-soliton is confirmed to be significant

Influence of off-grid/grid-connected operation on stability of large-scale photovoltaic system

Off-grid or grid-connected operation of large-scale photovoltaic system may cause stability problems. When the system performs off-grid operation, energy storage, as balance node, regulates power and frequency, then also influences stability. Under grid-connected operation, the external power system balances power and frequency regulation, and energy storage only equilibrium wave power. Although a detailed model for a single photovoltaic generation system has been established, the connection of numerous photovoltaic units is difficult to model and simulate, and it can easily cause dimension disaster. In order to analyze stability effectively of off-grid/grid-connected operation of large-scale photovoltaic system, we first establish the equivalent model of a photovoltaic farm through the method of dynamic aggregation of wind turbines, and then obtain indicators affecting the stability considering the reactance matrix of the transmission line. When the real part of the oscillation mode sensitivity index is greater than zero, oscillation mode approaches the imaginary axis, indicating that the PV system stability deteriorates. Conversely, the PV system is regionally stable. Finally, the effects of the number of photovoltaic units and transmission line length on stability are theoretically analyzed, and the theoretical derivation is validated through simulations. More PV units and a longer transmission line increase the likelihood of instability through the sensitivity of the oscillation mode

The Transition Phenomenon of (1,0)-<i>d</i>-Regular (<i>k</i>, <i>s</i>)-SAT

For a d-regular (k,s)-CNF formula, a problem is to determine whether it has a (1,0)-super solution. If so, it is called (1,0)-d-regular (k,s)-SAT. A (1,0)-super solution is an assignment that satisfies at least two literals of each clause. When the value of any one of the variables is flipped, the (1,0)-super solution is still a solution. Super solutions have gained significant attention for their robustness. Here, a d-regular (k,s)-CNF formula is a special CNF formula with clauses of size exactly k, in which each variable appears exactly s-times, and the absolute frequency difference between positive and negative occurrences of each variable is at most a nonnegative integer d. Obviously, the structure of a d-regular (k,s)-CNF formula is much more regular than other formulas. In this paper, we certify that, for k≥5, there is a critical function φ(k,d) such that, if s≤φ(k,d), all d-regular (k,s)-CNF formulas have a (1,0)-super solution; otherwise (1,0)-d-regular (k,s)-SAT is NP-complete. By the Lopsided Local Lemma, we get an existence condition of (1,0)-super solutions and propose an algorithm to find the lower bound of φ(k,d)