Hasil untuk "Control engineering systems. Automatic machinery (General)"

Chantal Barwig, Ruchira Colaco, Alina‐Sophie Koch et al.

Miniaturized bistable actuators are of notable relevance for applications in microfluidics or the manipulation of delicate objects. Many applications require actuators to be multistable, meaning that they can hold specific positions without continuous energy input. However, reversibly controllable soft actuators, especially those based on thermoresponsive materials, typically lack this capability. To overcome this challenge, bistable soft microactuators fabricated by two‐photon polymerization at micrometer precision are demonstrate here, allowing for arbitrary 3D shapes. The bistability is given by material composition, that is, poly(N‐isopropylacrylamide) (pNIPAM) and a light‐responsive azobenzene compound. The incorporation of an azobenzene into pNIPAM photoresin enables the modification of its lower critical solution temperature (LCST) through the (E)–(Z)‐isomerization, allowing for two states: a swollen and shrunken state. Hereby, actuation, in terms of shrinking and swelling, is controlled by photoswitching, allowing for the actuation of Azo_pNIPAM microactuators within a constant ambient temperature regime. Moreover, the pNIPAM moiety also allows thermal actuation when it contains either isomer, ((E) or (Z)), when the ambient temperature exceeds the LCST. Temperature and light changes are applied to characterize the bistable nature of the microactuators and an application of those bistable microactuators in a lab‐on‐a‐chip device is shown.

Samai Meriem, Ghedjati Keltoum, Abdelaziz Mourad

Hao-Yi Chih, Tanveer Ahmed, Amy P. Chiu et al.

Scoring sleep stages is an essential procedure for the diagnosis of sleeping disorders. Conventional sleep staging is a laborious and costly procedure requiring multimodal biological signals and an expert for the assessment. There has always been a demand for approaches which can exempt the need to going through diagnostic procedures under specialized facilities and enable automated sleep staging. Herein, a high‐performance multitask learning model enabling high‐accuracy sleep staging using heart rate data is reported. The proposed algorithm exhibits superior performance with reduced computational resource in comparison with the competing machine and deep learning algorithms when trained and evaluated using electrocardiography and photoplethysmogram (PPG) data. The reported model consumes ≈7.5 times less training parameters and ≈75% less amount of input data than the previously reported models and yields better or comparable performance (mean per night accuracy of 77.5% and Cohen's kappa of 0.643). To demonstrate its potential for wearable electronics, the reported algorithm is implemented in a fully integrated watch. The reported integrated watch is a stand‐alone fully functional platform, which automatedly captures PPG data from the subject's wrist, predicts sleep stages, and displays the result on a screen as well as an associated smartphone application.

Rihard Karba, Juš Kocijan, Tadej Bajd et al.

R. Chitra, S N Supradha, Durgashree T et al.

Changchun Wu, Hao Liu, Senyuan Lin et al.

In wearable robotics, soft actuation principles have been increasingly explored and tested due to their safety and comfort in human–robot interactions. Herein, a braided flat‐tube artificial muscle (BFAM) is presented. BFAMs are fabricated by braiding cotton threads together with an inexpensive lay‐flat tube (LFT) in a specific conform‐to‐LFT weaving method. They generate uniaxial contractions when powered by compressed fluids. The basic structure and working mechanism of the proposed BFAM are explained, and a quasistatic model is also developed. A comparison with other fluidic driven soft actuators is made and tabulated. Based on experimental studies, the proposed BFAM can contract close to 30% and yield force outputs more than 150 times their weight at an air pressure of 0.12 MPa. BFAM can be braided with multiple layers of flat tube without large increase of size. Experimental studies have shown that more layers of flat tube give a larger strain and output force up to four layers, beyond which layer increase does not yield visible improvement in strain and output force. Finally, potential applications of BFAM to arm joint actuations are illustrated to show its easy fitting to wearable robotics.

Juan Sebastián Montenegro-Bravo, Juan David Ruiz-Flórez, Juan David Romero-Ante et al.

Las operaciones pick-and-place son las más frecuentes en aplicaciones robóticas, y muchas veces su diseño incluye la presencia de obstáculos. En este trabajo se presenta la construcción de una plataforma software que permite la manipulación de un robot colaborativo UR3e mediante la generación de trayectorias 3D facilmente definidas por el usuario, además de una de pinza blanda capaz de sujetar objetos con diferentes geometrías. Para ello, se detalla el desarrollo de una interfaz gráfica en Unity, así como la incorporación del gemelo digital del robot UR3e. Del mismo modo, se exponen los diferentes módulos que permiten la comunicación de la plataforma con el manipulador a través de ROS. Los resultados muestran la creación de rutas adaptadas por el usuario ante diferentes casos en zonas de colisión y la disposición de la pinza para sujetar diferentes objetos. También se compara el error deprecisión entre los datos enviados respecto a los que se reciben desde el robot durante el seguimiento de trayectorias definidas por el usuario.

Steven X. Ding, Linlin Li

Dapeng Liu, Qianqian Shi, Junyao Zhang et al.

2D metal–organic frameworks (2D‐MOFs) have been extensively studied as promising materials in the fields of electrocatalysis, drug delivery, electronic devices, etc. However, few studies have explored the application potential of 2D‐MOFs in novel neuromorphic computing devices. Herein, an optoelectronic neuromorphic transistor based on a 2D‐MOF/polymer charge‐trapping layer is reported. It is found that the large specific surface area, stable crystal structure, and highly accessible active sites in 2D‐MOFs make them excellent charge‐trapping materials for the devices, which are beneficial for mimicking the memory and learning functions observed in the organism's nervous systems. Different types of synaptic behaviors have been realized in the 2D‐MOF‐based neuromorphic devices under stimuli signal, e.g., paired‐pulse facilitation, excitatory postsynaptic current, short‐term memory, and long‐term memory. More interestingly, emotion‐adjustable learning behavior is realized by changing the value of the source–drain voltage. This work can shed light on the application of 2D‐MOFs in neuromorphic computing and will contribute to the further development of neuromorphic computing devices. An interactive preprint version of the article can be found at DOI: https://doi.org/10.22541/au.165530836.62586068/v1.

Lijuan Zhu, Chengyun Zhu

The absolute stability problem of discrete-time time-delayed Lur'e systems with sector bounded nonlinearities is investigated in this paper. Firstly, a modified Lyapunov-Krasovskii functional (LKF) is designed with augmenting additional double summation terms, which complements more coupling information between the delay intervals and other system state variables than some previous LKFs. Secondly, some improved delay-dependent absolute stability criteria based on linear matrix inequality form (LMI) are proposed via the modified LKF and the relaxed free-matrix-based summation inequality technique application. The stability criteria are less conservative than some results previously proposed. The reduction of the conservatism mainly relies on the full use of the relaxed summation inequality technique based on the modified LKF. Finally, two common numerical examples are presented to show the effectiveness of the proposed approach.

WU Chundong, LI Yun, ZHANG Jingyan

In EV/HEV application, the maximum internal temperature allowed for film capacitor should be less than 105 ℃, which leaves especial limited temperature margin as the capacitor works in high ambient temperature of 85 ℃. However, temperature rising of capacitor is strongly related to the load condition. And it is difficult to define the temperature allowance of capacitor accurately in the early design. For this purpose, a consolidated electrothermal simulation method based Foster thermal network model is presented in this paper to predict the transient temperature inside the capacitor. To set up a complete simulation model, the parameters of five-order Foster resistor-capacitor thermal network model are extracted by the method of capacitor temperature rise experiment. The temperature rising of film capacitor in the conditions of NEDC (New European Driving Cycle) & USA highway driving cycle is calculated by the complete simulation model. Simulation results show that a good correspondence is presented between capacitor temperature rising curve vs ripple current under driving cycle, and the maximum temperature rise can be clearly assessed by this temperature prediction method.

Tien-Chin Wang, Thuy T Thu Nguyen, Binh N Phan

The development in both quantity and quality of the system of private universities over the past time has created great opportunities for people to study and improve their qualifications and working skills. It is also challenging for educational managers to find the right university development strategy in today's competitive environment. Therefore, evaluating the effectiveness of using private universities resource to analyze training performance is considered one of the issues. In this study, the Entropy method is used to determine the weight of the criteria. Then the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is used to determine the ranking order of the private universities. Next, Spearman's rank correlation coefficient was applied to evaluate the correlation between rank-ordered variables over the 2 years of analysis selection. Finally, ANOVA was used to compare the criteria between groups of universities. The combination of methods contributes to creating an objective environment in assessing the performance of each university. Thereby, universities can see the important criteria to pay attention to, creating a premise for universities to establish strategies for development and competition. At the same time, educational leaders have the right perspective in choosing key universities to invest in finance and facilities.

Sang-In Bae, Sangyeon Lee, Jae-Myeong Kwon et al.

Facial expression conveys nonverbal communication information to help humans better perceive physical or psychophysical situations. Accurate 3D imaging provides stable topographic changes for reading facial expression. In particular, light‐field cameras (LFCs) have high potential for constructing depth maps, thanks to a simple configuration of microlens arrays and an objective lens. Herein, machine‐learned NIR‐based LFCs (NIR‐LFCs) for facial expression reading by extracting Euclidean distances of 3D facial landmarks in pairwise fashion are reported. The NIR‐LFC contains microlens arrays with asymmetric Fabry−Perot filter and NIR bandpass filter on CMOS image sensor, fully packaged with two vertical‐cavity surface‐emitting lasers. The NIR‐LFC not only increases the image contrast by 2.1 times compared with conventional LFCs, but also reduces the reconstruction errors by up to 54%, regardless of ambient illumination conditions. A multilayer perceptron (MLP) classifies input vectors, consisting of 78 pairwise distances on the facial depth map of happiness, anger, sadness, and disgust, and also exhibits exceptional average accuracy of 0.85 (p<0.05). This LFC provides a new platform for quantitatively labeling facial expression and emotion in point‐of‐care biomedical, social perception, or human−machine interaction applications.

HUANG Zhixiong, ZHANG Yitian, LI Zhiyong et al.

The relationship between received power and load variation in magnetic coupling resonant wireless power transmission (MCR-WPT) system has received wide attention, and it is strongly correlated with the topology and coupling coefficient. This paper conducts research on the MCR-WPT system with rectifier circuit, and the expression of received power was obtained by establishing the equivalent circuit model of four topologies. Further analysis shows that the load response characteristics of power are significantly affected by the topological structure and coupling coefficient. The maximum power points of the series-series (SS) topology and the parallel-parallel (PP) topology are slightly biased toward the high impedance region. The maximum power point of the series-parallel (SP) topology and the parallel-series (PS) topology are biased toward the low impedance region. Finally, based on the load response characteristics of each topological structure is verified the simulation analysis and experiments, reference suggestions are provided on how the MCR-WPT system should select the topology in different application environments to achieve maximum power transmission.

Caixia Huang, Fei Lei, Xu Han et al.

The analysis and control of powertrain systems of electric vehicle, which is an important type of new energy vehicle, have been the focus of extensive research, but determining the motor modeling parameters remains a problem. A method of parameter determination for brushless DC motor modeling based on vehicle power performance was developed in this study. The power and torque of the driving motor of an electric vehicle were obtained by using the dynamic equation of the electric vehicle to satisfy the requirements of power performance. The ranges of the back electromotive force coefficient and the winding inductance were derived from the voltage and dynamic equations of brushless DC motor, which were deduced from the expected power and torque of the motor. The modeling parameters were then determined on the basis of the influence of power source voltage, back electromotive force coefficient, winding inductance, and winding resistance on vehicle power performance. A hardware-in-loop simulation of vehicle power performance was performed to verify the effectiveness of the proposed method. Results indicate that the maximum vehicle velocity is 172 km/h, and the acceleration time of 100 km/h is 13 s, which reveal that the motor modeling parameters obtained with the method satisfy relevant requirements.

Xingsi Xue, Junfeng Chen

Although biomedical ontologies have been widely used in the life science domain, the heterogeneous problem among biomedical ontologies hampers their inter-operability. Thus, the establishment of meaningful links between heterogeneous biomedical ontologies, so-called biomedical ontology matching, is critical to the success of biomedical ontology engineering. To determine the biomedical ontology alignment with high quality, in this work, a Hybrid Compact Differential Evolution (HCDE) algorithm-based biomedical ontology matching technique is proposed. In particular, we propose a similarity metric on biomedical concepts, construct an optimal model for the biomedical ontology matching problem, and introduce a binomial crossover into CDE's evolving the process to enhance its performance. The experiments are carried out on the Disease and Phenotype track and Biodiversity and Ecology track from the Ontology Alignment Evaluation Initiative (OAEI 2018). The experimental results show that HCDE can significantly improve the CDE in terms of the alignment's quality, and the alignments obtained by HCDE are also better than OAEI 2018's participants.

J. Fernández de Cañete, C. Galindo, J. Barbancho et al.

Eduardo Trutié-Carrero, Damian Valdés-Santiago, Ángela León-Mecías et al.

Burst in water distribution systems causes great loss of this natural resource, interrupts the water supply, damages the streets, builds and increases the transmission of infectious diseases. In this paper we propose a new algorithm that allows the detection and automatic localization of burst in water distribution systems. As for detection, the novelty is to use the wavelet correlation criterion to compute the statistical decision and compare it with a detection threshold. The novelty in the localization is to use the statistical operator cross-correlation. The algorithm was implemented in Octave and was validated with 32 signals acquired in the laboratory in a 26.7 m long steel pipe. In 16 signals burst were triggered which were detected under a false positive probability of 2 %. No false positives were present on the 16 signals where only noise was present.

GUAN Rende, TANG Zhou, LIAO Yuanhui et al.

It introduced the engineering design and techincal specifications of a 500kW grid-connected photovoltaic inverter with double modules paralleling. With multi-mode optimal running characteristics of dual MPPT based on single core respectively control and dual modules parallel power system, this PV grid-connected inverter not only has good performances such as compact volume, friendly operation, maintenance in the front ,etc, but also has good reliability, availability, maintainability and safety.

罗凌波, 戴计生, 尚敬

Customers’ ability in secondary programmable and debugging development plays an important role in converter industry with requirements of lower cost and celerity. It proposed a secondary development software CSR_Drive for converter, described its structure, model function and system features, and presented an application example. The detailed design process was described including parameter management, functional connectivity, online monitoring, main-circuit state machine, program updating and system security. Actual operation results show that the proposed software is powerful, stable and reliable.