Most industrial robots are not capable of teaching by hand and require path points to be specified by teaching pendants. To enable the teaching of industrial robots by hand without any force sensors, ...this paper proposes a scheme to minimize the external force estimation error and reduce disturbance in the guiding task by using the virtual mass and virtual friction model. In this case, the maximum velocity and acceleration of the robot end effector shall be limited to ensure safety. Thus, the operator is allowed to guide the robot by hand. The joint torque is obtained from the motor current. The inertial force and friction of the links and driving systems are analyzed. The nonlinear dynamic model of the industrial robot is built and its parameters are calibrated by a nonlinear method. The force estimation is referenced to set the virtual friction and to design the force-following controller. Hence the end effector can follow the direction of external force compliantly and suppress jitters. Finally, several experiments on a six degrees of freedom industrial robot demonstrate the validity of the proposed control scheme.
Endowing the robot with tactile perception can effectively improve manipulation dexterity, along with various benefits of human-like touch. Using GelStereo (GS) tactile sensing, which gives ...high-resolution contact geometry information, including 2-D displacement field, and 3-D point cloud of the contact surface, we present a learning-based slip detection system in this study. The results reveal that the well-trained network achieves 95.79% accuracy on the never-seen testing dataset, which surpasses the current model-based and learning-based methods using visuotactile sensing. We also propose a general framework for slip feedback adaptive control for dexterous robot manipulation tasks. The experimental results show the effectiveness and efficiency of the proposed control framework using GS tactile feedback when deployed on real-world grasping and screwing manipulation tasks on various robot setups.
We investigated the layer-number-dependent work function of MoS
2
nanoflakes by using Kelvin probe force microscopy (KPFM) to measure the surface potential. The work functions of as-prepared 1- to ...6-layer MoS
2
nanoflakes were 5.15–5.39 eV and increased with increasing layer number. After annealing, the work functions of the nanoflakes decreased to 0.1–0.2 eV due to elimination of absorbed molecules on the surface. However, the work function of the edge region of the annealed flakes was relatively larger than that of the internal region. The charge carrier trapping by adsorbed molecules due to the polarity and the hydrophilicity of MoS
2
may cause a reduction in the work function of the annealed flakes compared with that for MoS
2
exposed to air. The dependence of the obtained work function of MoS
2
nanoflakes on the number of layers is essential to the formation of metal contacts for fabricating future MoS2-based devices.
The detection of PCB defect quality plays an important role in PCB fabrication. However, the size of the PCB defects is too small to identify. In order to improve the detection efficiency of existing ...algorithms, a joint multiscale PCB defect target detection and attention mechanism, which named RAR-SSD, was proposed. By using lightweight receptive field block module (RFB-s) with an attention mechanism module, we built a wider range of effective focused features, which exploited the importance of different features in different channels without increasing the computing power of the network. In addition, we built a feature fusion module to efficiently fuse low-level feature information with high-level feature information to produce a more complete feature map and improve the accuracy of fault recognition. The proposed network improved the fault recognition accuracy of PCBs by 2.23% over the original SSD algorithm, with a recall rate of 6.51% and an F1 value of 4.85%, the model has greatly improved in terms of detection performance. The optimized algorithm has significant speed and accuracy advantages over the algorithms YOLOv3 and YOLOv5. Experimental results show that the proposed RAR-SSD model has good performance in detecting small and medium size targets for defects in the PCB manufacturing process and is of some guidance for the subsequent detection of PCB defects.
•Interval linguistic hesitant fuzzy preference relations are presented.•An additive consistency concept is defined.•Models for judging consistency and determining missing values are constructed.•Two ...equivalent methods for ranking objects are provided;•An additive consistency and consensus-based algorithm is developed.
This paper introduces a new type of fuzzy sets called interval linguistic hesitant fuzzy sets (ILHFSs), which can address the qualitatively uncertain preferences of decision makers as well as reflect their hesitancy. Such fuzzy sets endow the decision makers with more flexibility: (i) several interval linguistic variables are allowed to represent a judgment, and (ii) the number of interval linguistic variables can be different for different preferences. To show the application of ILHFSs, a group decision-making method with interval linguistic hesitant fuzzy preference relations (ILHFPRs) is introduced. To achieve this goal, an additive consistency concept for ILHFPRs is presented to derive the rational rankings. Following this concept, a programming model for judging the additive consistency of ILHFPRs is constructed. Then, an additive consistency-based programming model is established to ascertain missing values in incomplete ILHFPRs. Subsequently, an approach for calculating the interval linguistic hesitant fuzzy priority weight vector from incomplete and inconsistent ILHFPRs is presented. To measure the agreement degree of the decision makers’ judgements, a consensus index is offered, and a method for determining the weights of the decision makers is proposed. Finally, a numerical example about evaluating commodity sales platforms in China is chosen to illustrate the utilization of the new method. The results extend and perfect the application scope of preference relations, which offer the decision makers more choices to express their judgments.
The thiophene-derived amido bis-nitrogen mustard N2,N2,N5,N5-tetrakis（2-chloroethyl）-3,4-dimethylthio- phene-2,5-dicarboxamide was designed and synthesized via five-step reactions from commercially ...available 2-chloroacetonitrile. This target compound was confirmed by 1H NMR, 13C NMR, MS, IR spectra and elemental analyses, and its structure was further characterized by X-ray single-crystal analysis. The biological activities for the title compound and some intermediates were evaluated in vitro for their antibacterial, antifungal and cytotoxic activities. The preliminary results showed that the title compound could inhibit efficiently the growth of the tested microorganisms including drug-resistant bacteria MRSA to some extent. Moreover, the target compound was found to be effective against prostatic carcinoma cell line （PC-3）, breast carcinoma cell line （MCF-7）, colon carcinoma （LoVo） and lung cancer （A549）. Especially, it gave selective antitumor efficacy against prostatic carcinoma cell line （PC-3） at a low dose. Keywords nitrogen mustard, thiophene, antibacterial, antifungal, cytotoxicity
This paper aims to offer an intuitionistic triangular fuzzy group decision making method by preference relations. For this purpose, the concept of intuitionistic triangular fuzzy preference relations ...(ITFPRs) is first offered. Then, an additive consistency concept for ITFPRs is introduced. Meanwhile, a programming model is built to check the consistency of ITFPRs. Considering the case where incomplete ITFPRs are obtained, two programming models are constructed, which aim at maximizing the consistency and minimizing the uncertainty of missing information. To achieve the goals of the minimum total adjustment and the smallest number of adjusted elements, two programming models are established to repair inconsistent ITFPRs. In addition, the weights of decision makers are considered, and the consensus levels of individual ITFPRs are studied to ensure the representativeness of decision results. When individual ITFPRs do not meet the consensus requirement, a programming model to reach the consensus threshold is constructed, which permits different intuitionistic triangular fuzzy variables (ITFVs) to have different adjustments and minimizes the total adjustment. Finally, a group decision making algorithm with ITFPRs is proposed, and its feasibility and efficiency are demonstrated through an example of evaluating the intelligent traditional Chinese medicine decocting centers.
In this work, Pt nanoparticles-decorated urchin-like W18O49 microspheres are synthesized by a simple hydrothermal-photodeposition method, and the effect of a contact created between Pt nanoparticles ...and W18O49 nanorods on response, sensitivity, detection limit, and recovery time in ethanol gas sensing is explored. Transmission electron microscopy (TEM) results confirm the successful deposition of Pt nanoparticles with a size of 5–10 nm on the W18O49 nanorods. The deposition of Pt nanoparticles on the surface of W18O49 nanorods significantly enhances a gas-sensing performance for 10 ppm ethanol at 300 °C (with a response value of 22). Compared to the W18O49 sensor, the Pt/W18O49 sensor exhibits faster response-recovery time, lower detection limit, higher response value, and excellent selectivity for detection of ethanol gas. Furthermore, the Pt/W18O49 sensor also shows a fast response-recovery time of 28.5 s and 14.3 s toward 200 ppb ethanol. The results from gas chromatography demonstrate a significant difference between Pt/W18O49 and W18O49 sensors in the efficiency of ethanol conversion to CO2. The interface electron-transfer mechanism between the Pt and W18O49 is further studied by density functional theory (DFT) calculations, providing theoretical insights into the adsorption energy and activation ability of Pt/W18O49 and W18O49 for oxygen and ethanol molecules. The DFT results reveal that an Ohmic contact is formed at the Pt/W18O49 interfaces, indicating the enhanced ability of electron transfer and increased activation of gas molecules. Moreover, the influence of the Ohmic contact on the enhancement of the ethanol gas sensing performance is discussed via electron depletion theory. This study demonstrates a superior performance of Pt-modified W18O49 in ethanol gas detection with theoretical and experimental insights into the mechanism for enhanced ethanol gas sensing.
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•Pt/W18O49 sensor with excellent gas-sensing performance were constructed.•The formation of Ohmic contact improved the interfacial charge transfer ability.•the interface mechanism effect between the Pt nanoparticles and W18O49 were explored via DFT.•The adsorption-activation energy of Pt/W18O49 and W18O49 sensor were discussed.•the amount of ethanol consumed and carbon dioxide generated in the reaction process between the W18O49 and Pt/W18O49 sensors were explored via gas chromatograph.
With the rapid economic development of Beijing-Tianjin-Hebei region, the problem of environmental pollution cannot be ignored. Especially in recent years, the haze weather, the increase of carbon ...dioxide emissions, the development of Beijing, Tianjin and Hebei has brought a negative impact. Now, the primary energy consumption of the three regions of Beijing, Tianjin and Hebei is decomposed into five factors including population, economy, industrial structure, energy intensity and energy consumption structure by using LMDI decomposition method. The results show that: overall population and per capita GDP promote the growth of carbon emissions, and overall industrial structure effect, energy intensity effect and energy consumption structure factors inhibit the growth of carbon emissions. The energy intensity of the secondary industry and the tertiary industry has a very significant inhibiting effect on the growth of carbon emissions.
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•Theoretical assessment on chirality-, width- and functionalization-dependent work function of Ti2B (MBene) nanoribbon is performed by DFT study.•The work function of Ti2B nanoribbons ...has been discussed in terms of the non-equivalent edges and the halogen termination.•The work function variation of the Ti2B nanoribbons has been explained by the edge dipole moments caused by the edge’s charge redistribution, halogen electronegativity, and edge reconstruction.
One-dimensional nanoribbons have foreshadowed potential applications in nanoelectronics due to their fascinating quantum confinement effects. We present theoretical assessment from first-principles calculations to explore the work functions of Ti2B-based MBene nanoribbons, focusing on the size, edge, and functionalization dependencies. We found that the bare and halogen-functionalized Ti2B nanoribbons exhibit metallic properties and chemical stability. The work function of both bare and halogen-terminated armchair Ti2B nanoribbons tends to saturate as width. In contrast, the work function of zigzag Ti2B nanoribbons varies complexly with width and has been discussed in terms of the non-equivalent edges and halogen termination. The work functions of halogen-terminated Ti2B nanoribbons have been found to be significantly affected by the edge dipole moments, which are determined by three factors: functionalization-induced electron redistribution at the edge, the electronegativity of halogen functional groups, and the edge reconstruction. These findings provide valuable insights for designing, characterizing, and utilizing the proposed nanostructures.
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