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This work investigated the signal reception from multipath including direct transmission and reflection paths in a non-contact gas flow measurement system based on air-coupled leaky Lamb waves. Analytical model was established to provide the multiple reflective signal propagation time differences between upstream and downstream paths at different flow velocities. A multiphysics model based on finite element methods was established to facilitated the visualisation of the leaky Lamb waves reflected between the plates and the Lamb waves excited by multiple reflective paths waves. The propagation time differences were evaluated by performing simulations and experiments, which are in good agreement with the analytical values (RMSE are 0.0708 and 0.0767 respectively). The receiver can collect multipath signals at a large distance separated from the transmitter. Time resolution is enhanced by using received signals from reflection paths, as the transit time increased with the ultrasound path between the transducers.

Emergency evacuation is an important issue in public security. To make a considerate plan, various situations are presented including blocking the accident area and letting the emergency access path available. In order to offer dynamic evacuation routes due to different circumstances, a multistory building evacuation model is proposed. Firstly, to analyse the patency of the building, an evacuation formula is applied after binary processing. The function of evacuation time and some other parameters is given by means of regression analysis. Secondly, the cellular automata (CA) algorithm was applied to illustrate the effect of the bottleneck. The response of evacuation time could be approximately optimized through calculating time step of the CA simulation. Finally, the value of maximum evacuation population density could be determined according to the analysis of CA simulation results, which was related to the switch state of the emergency channel. The emergency evacuation model was simulated by using the Louvre museum as an example. The results of the simulation presented some feasible evacuation routes in all kinds of situations. Furthermore, the functional relationship would also be given among evacuation time with the diversity of tourists, pedestrian density, and width of exits. It can give a different perspective that the multistory building evacuation model shows excellent adaptability to different circumstances.

Reinforcement learning based control is an effective approach to traffic light control. In terms of the Deep Q-learning Network (DQN) based traffic light control method, the reward function should be carefully designed, as it affects the performance of the control method and it also brings the challenge in standardized design. Thus, the control method would fail to perform well if the reward function was established improperly. If the reward function was too complicated, it would be time-consuming for the algorithm. To solve this problem, we proposed an intersection-model based reward function in the DQN algorithm. We investigated the different types of urban road intersection structures and analyzed their features. Then we used those features to formulate the reward function. Our model was evaluated via the simulation dataset under different road situations and got less emergency stop with 14%~32% improvement while the number of passing vehicles was also a bit more than the baseline. There were also 22% and 7% speedup in the training process under the tow training process.

Lamb wave showed the possibilities in ultrasonic inspection technique by analyzing its propagation characteristics, which resulted from the rapid increase in the availability of computing simulation in recent years. These propagation characteristics may be modified to consider the influences of the fluid when plates loaded with liquid droplets. Hence, a coupled plate-droplet system of diffuse-interface was established in this paper, which includes three sub-domains: air, sensor, and plate system. The situation for liquid droplets on the different surface of a single thin plate was compared with the plate without liquid droplets. By calculating a proper separation to locate the transducers on both sides of a thin isotropic plate, the Lamb waves excited from the plate generated its leaky waves into the air domain and the leaky waves detected by the receiver successfully in the simulation. The propagation of Lamb waves and the leaky waves were further visualized by the coupled plate-droplet system based on COMSOL Multiphysics®. The characteristics of Lamb wave propagation differed for the presence of droplets on different surfaces of the plate were discussed by signals analysis. Ultimately, the signals analysis has verified that the received signals were reshaped due to the existence of liquid droplets, and the solution derived with COMSOL Multiphysics® on finite element method led to a thorough understanding of the coupled plate-droplet system and the effect of liquid droplets.

Traffic congestion has become serious across the world since the recent two centuries. Among existing control methods, Deep Q-learning Network (DQN) based reinforcement learning achieved superior performance over state-of-art methods. Reward function is a crucial part of reinforcement learning. Different terms in reward function guide the agent attaining different goals. In traffic light control problem, the reward function could be either too simple to perform well or too complicated to find the best parameters. It influents the performance of the algorithm and bring the challenge in the standardized design of the control algorithm. Amid at this problem, we proposed a road model based reward function and applied it in DQN algorithm. The road structure was introduced and modelled, then from this model we then took factors which can represent different car flow and different road situation. Also, they were easily obtained from the real world. Those factors were applied to design the reward function. Experiments with simulation dataset showed the efficiency of the road model based reward function in the DQN algorithm.

The signals in an air-coupled ultrasonic inspection system using Lamb waves would be affected by liquid droplets on the surface of test plates. To investigate the wave behaviour, a plate-droplet inspection system comprising a thin isotropic plate loaded with water droplets and a pitch–catch transducer configuration was modelled and studied experimentally. The Lamb waves were generated by a non-contact airborne transmitter. Their energy leaking into the adjacent air was collected by a receiver. To obtain a deep understanding of the effects of water droplets, a multiphysics model based on finite element method was established. The model facilitated the visualization of the wave fields scattered by the droplets on the surface of the plate and evaluated the received signals which were then verified by experimental measurements. This entirely modelling method could be a convenient way to interpret the inspection signals for test plate loaded with liquid droplets.

Air-coupled ultrasonic inspection using leaky Lamb waves offers attractive possibilities for non-contact testing of plate materials and structures. A common method uses an air-coupled pitch-catch configuration, which comprises a transmitter and a receiver positioned at oblique angles to a thin plate. It is well known that the angle of incidence of the ultrasonic bulk wave in the air can be used to preferentially generate specific Lamb wave modes in the plate in a non-contact manner, depending on the plate dimensions and material properties. Multiple reflections of the ultrasonic waves in the air gap between the transmitter and the plate can produce additional delayed waves entering the plate at angles of incidence that are different to those of the original bulk wave source. Similarly, multiple reflections of the leaky Lamb waves in the air gap between the plate and an inclined receiver may then have different angles of incidence and propagation delays when arriving at the receiver and hence the signal analysis may become complex, potentially leading to confusion in the identification of the wave modes. To obtain a better understanding of the generation, propagation and detection of leaky Lamb waves and the effects of reflected waves within the air gaps, a multiphysics model using finite element methods was established. This model facilitated the visualisation of the propagation of the reflected waves between the transducers and the plate, the subsequent generation of additional Lamb wave signals within the plate itself, their leakage into the adjacent air, and the reflections of the leaky waves in the air gap between the plate and receiver. Multiple simulations were performed to evaluate the propagation and reflection of signals produced at different transducer incidence angles. Experimental measurements in air were in good agreement with simulation, which verified that the multiphysics model can provide a convenient and accurate way to interpret the signals in air-coupled ultrasonic inspection using leaky Lamb waves.

Mass spectrometry (MS) is an important technique in protein research. Effective classification methods by MS data could contribute to early and less-invasive diagnosis and also facilitate developments in the bioinformatics field. As MS data is featured by high dimension, appropriate methods which can effectively deal with the large amount of MS data have been widely studied. In this paper, the applications of methods based on intelligence algorithms have been investigated. Firstly, classification and biomarker analysis methods using typical machine learning approaches have been discussed. Then those are followed by the Ensemble strategy algorithms. Clearly, simple and basic machine learning algorithms hardly addressed the various needs of protein MS classification. Preprocessing algorithms have been also studied, as these methods are useful for feature selection or feature extraction to improve classification performance. Protein MS data growing with data volume becomes complicated and large; improvements in classification methods in terms of classifier selection and combinations of different algorithms and preprocessing algorithms are more emphasized in further work.

Travel time estimation plays a core role in intelligent traffic systems, as people or smart vehicles can choose a better travel route in advance, while local authorities can make urban traffic planning based on it. The paper proposes a dual traffic network topology coupled with improved delay models to estimate travel time in urban traffic system. The structure of the system is demonstrated by the dual traffic network (DTN) topology. It hires nodes to representjoint points of links and intersections; it also has two kinds of edges-links and turning cases of intersections. The BPR model is improved by concerning the influence of pedestrians and the lane width, and the HCM model is improved by adding travel time at intersections and considering three different turning cases to match with the DTN topology. The proposed methodology is evaluated by a comparison and an experiment in Changzhou, China. The error is greatly reduced, even though the degree of saturation exceeds 0.72. This proposed estimation methodology can improve the estimation accuracy significantly, especially in high degree of saturation cases.

This paper describes a completely non-contact ultrasonic method of gas flow metering using air-coupled leaky Lamb waves. To show proof of principle, a simplified representation of gas flow in a duct, comprising two separated thin isotropic plates with a gas flowing between them, has been modelled and investigated experimentally. An airborne compression wave emitted from an air-coupled capacitive ultrasonic transducer excited a leaky Lamb wave in the first plate in a non-contact manner. The leakage of this Lamb wave crossed the gas flow at an angle between the two plates as a compression wave, and excited a leaky Lamb wave in the second plate. An air-coupled capacitive ultrasonic transducer on the opposite side of this second plate then detected the airborne compression wave leakage from the second Lamb wave. As the gas flow shifted the wave field between the two plates, the point of Lamb wave excitation in the second plate was displaced in proportion to the gas flow rate. Two such measurements, in opposite directions, formed a completely non-contact contra-propagating Lamb wave flow meter, allowing measurement of the flow velocity between the plates. A COMSOL Multiphysics® model was used to visualize the wave fields, and accurately predicted the time differences that were then measured experimentally. Experiments using different Lamb wave frequencies and plate materials were also similarly verified. This entirely non-contact airborne approach to Lamb wave flow metering could be applied in place of clamp-on techniques in thin-walled ducts or pipes.

To improve the energy efficiency and output power of the piston compressed air engine (CAE), a mathematical model of its working process was set up. With the use of the MATLAB/Simulink software for simulation, the influences of the bore-to-stroke ratio, intake pressure and valve lift on the performance of the engine were obtained for the analysis of the energy efficiency and the output power. Moreover, to optimize the energy efficiency of the engine with the given output power, an improved NSGA-II was introduced, and a series of optimization intake pressures and valve lifts was obtained. When the output power value is about 2 kW, the intake pressure and the intake valve lift can be set to 1.99 MPa and 9.99 mm, the energy efficiency is highest: 31.17%. Finally, that the improved NSGA-II is superior to NSGA-II in proximity and diversity has been proved. This research can be referred in the optimization of the piston CAE and provides a method for the energy efficiency optimization study. Kurjenje fosilnih goriv je eden glavnih vzrokov resnih okoljskih problemov, kot so učinek tople grede, tanjšanje ozonske plasti in smog. V članku je predstavljena nova vrsta pogonske opreme, ki bi lahko pomagala pri odpravljanju teh problemov. Batni motor (CAE) poganja stisnjen zrak, ki ga je mogoče pridobiti z uporabo obnovljivih virov, kot so sončna svetloba, veter in bibavica. Batni motorji CAE so okolju prijazna oprema in bi jih lahko vgrajevali v vozila prihodnosti, njihov razvoj pa je začasno zavrla nizka energetska učinkovitost.

In many practical applications of air-coupled ultrasonic inspection, the accurate direction of the wavefronts of the ultrasound in air is unknown. Thereby, the wave may reach the transducer at an oblique incidence angle. It may lead to misinterpretation of the waveform of the measured wave. This work investigated the quasi-dispersion of planar-wave signal affected by the receiving angle. An analytical model represented as a simplified model implementation was proposed to provide a theoretical prediction of the received signal. A numerical multiphysics model established by COMSOL Multiphysics® was used to demonstrate the signal reception by wavefield visualization. Simulational signals were in excellent agreement with the signals from analytical model. Finally, experiments with the similar configurations of transducers used in analytical and simulational models were conducted. The results confirmed that quasi-dispersion of the air-coupled ultrasonic signal which is highly dependent on incidence angle and wavelength.

The conventional ultrasonic method for compressed air leak detection utilizes a directivity-based ultrasonic leak detector (DULD) to locate the leak. The location accuracy of this method is low due to the limit of the nominal frequency and the size of the ultrasonic sensor. In order to overcome this deficiency, a method based on time delay estimation (TDE) is proposed. The method utilizes three ultrasonic sensors arranged in an equilateral triangle to simultaneously receive the ultrasound generated by the leak. The leak can be located according to time delays between every two sensor signals. The theoretical accuracy of the method is analyzed, and it is found that the location error increases linearly with delay estimation error and the distance from the leak to the sensor plane, and the location error decreases with the distance between sensors. The average square difference function delay estimator with parabolic fitting is used and two practical techniques are devised to remove the anomalous delay estimates. Experimental results indicate that the location accuracy using the TDE-based ultrasonic leak detector is 6.5–8.3 times as high as that using the DULD. By adopting the proposed method, the leak can be located more accurately and easily, and then the detection efficiency is improved.

This paper proposes a non-intrusive and non-invasive method for measuring the gas flow rate in pneumatic industry. A heater unit is fixed on the partial circumference of the external wall of a pipeline and emits specific thermal pulses in a predetermined mode. Two sensors attached to the external wall detect the upstream temperature, and the gas flow can be measured according to the relationship between the flow rate and the dynamic thermal characteristics of the pipeline. To determine the preferable relationship, the temperature field model of the measurement system is built. Then, based on the measurement modes and the corresponding simulations, the objective functions for the gas flow specified on different dynamic thermal characteristics are established. Additionally, the minimum measurement time of the method, named reference time scale, is proposed. Further, robustness tests of the measurement method are derived by considering the influences of multiple factors on the objective functions. The experiments confirm that this method does not need to open the pipeline and disturb the flow regime in order to obtain the data; this method also avoids the typical time-consuming and complex operations, resists ambient temperature disturbance and achieves approximately acceptable results.

An improved denoising algorithm based on wavelet transform modulus maxima (WTMM) is proposed for processing non-intrusive measurement signals in pneumatic systems. Combined with the adaptive BayesShrink threshold and Witkin's scale space tracking theory, the process of tracing the evolution of WTMM over scales has been optimized. Thus, the signal and the noise can be identified and isolated effectively. Additionally, to improve the computational efficiency, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the signal. Numerical experiments confirm the advantages of the improved denoising algorithm: compared with the classical algorithm of WTMM, the improved denoising algorithm not only increases the signal to noise ratio by over 10% but also reduces the processing time by over 90%. More generally, the algorithm has better performance than that of several typical algorithms in its denoising quality, adaptability and practicality.